Various typo fixes - only in comments, no code changes.

Marlin/Marlin.h

 // Tonokip RepRap firmware rewrite based off of Hydra-mmm firmware.
-// Licence: GPL
+// License: GPL
 
 #ifndef MARLIN_H
 #define MARLIN_H
 # include "Arduino.h"
 #else
 # include "WProgram.h"
-  //Arduino < 1.0.0 does not define this, so we need to do it ourselfs
+  //Arduino < 1.0.0 does not define this, so we need to do it ourselves
 # define analogInputToDigitalPin(p) ((p) + A0)
 #endif
 
 void serial_echopair_P(const char *s_P, unsigned long v);
 
 
-//things to write to serial from Programmemory. saves 400 to 2k of RAM.
+//Things to write to serial from Program memory. Saves 400 to 2k of RAM.
 FORCE_INLINE void serialprintPGM(const char *str)
 {
   char ch=pgm_read_byte(str);
 
 bool IsStopped();
 
-void enquecommand(const char *cmd); //put an ascii command at the end of the current buffer.
-void enquecommand_P(const char *cmd); //put an ascii command at the end of the current buffer, read from flash
+void enquecommand(const char *cmd); //put an ASCII command at the end of the current buffer.
+void enquecommand_P(const char *cmd); //put an ASCII command at the end of the current buffer, read from flash
 void prepare_arc_move(char isclockwise);
 void clamp_to_software_endstops(float target[3]);
 

Marlin/Marlin_main.cpp

 
 #define VERSION_STRING  "1.0.0"
 
-// look here for descriptions of gcodes: http://linuxcnc.org/handbook/gcode/g-code.html
+// look here for descriptions of G-codes: http://linuxcnc.org/handbook/gcode/g-code.html
 // http://objects.reprap.org/wiki/Mendel_User_Manual:_RepRapGCodes
 
 //Implemented Codes
 // G30 - Single Z Probe, probes bed at current XY location.
 // G90 - Use Absolute Coordinates
 // G91 - Use Relative Coordinates
-// G92 - Set current position to cordinates given
+// G92 - Set current position to coordinates given
 
 // M Codes
 // M0   - Unconditional stop - Wait for user to press a button on the LCD (Only if ULTRA_LCD is enabled)
 // M31  - Output time since last M109 or SD card start to serial
 // M32  - Select file and start SD print (Can be used _while_ printing from SD card files):
 //        syntax "M32 /path/filename#", or "M32 S<startpos bytes> !filename#"
-//        Call gcode file : "M32 P !filename#" and return to caller file after finishing (simiarl to #include).
+//        Call gcode file : "M32 P !filename#" and return to caller file after finishing (similar to #include).
 //        The '#' is necessary when calling from within sd files, as it stops buffer prereading
 // M42  - Change pin status via gcode Use M42 Px Sy to set pin x to value y, when omitting Px the onboard led will be used.
 // M80  - Turn on Power Supply
 // M128 - EtoP Open (BariCUDA EtoP = electricity to air pressure transducer by jmil)
 // M129 - EtoP Closed (BariCUDA EtoP = electricity to air pressure transducer by jmil)
 // M140 - Set bed target temp
-// M150 - Set BlinkM Colour Output R: Red<0-255> U(!): Green<0-255> B: Blue<0-255> over i2c, G for green does not work.
+// M150 - Set BlinkM Color Output R: Red<0-255> U(!): Green<0-255> B: Blue<0-255> over i2c, G for green does not work.
 // M190 - Sxxx Wait for bed current temp to reach target temp. Waits only when heating
 //        Rxxx Wait for bed current temp to reach target temp. Waits when heating and cooling
 // M200 D<millimeters>- set filament diameter and set E axis units to cubic millimeters (use S0 to set back to millimeters).
 // M201 - Set max acceleration in units/s^2 for print moves (M201 X1000 Y1000)
 // M202 - Set max acceleration in units/s^2 for travel moves (M202 X1000 Y1000) Unused in Marlin!!
 // M203 - Set maximum feedrate that your machine can sustain (M203 X200 Y200 Z300 E10000) in mm/sec
-// M204 - Set default acceleration: S normal moves T filament only moves (M204 S3000 T7000) im mm/sec^2  also sets minimum segment time in ms (B20000) to prevent buffer underruns and M20 minimum feedrate
+// M204 - Set default acceleration: S normal moves T filament only moves (M204 S3000 T7000) in mm/sec^2  also sets minimum segment time in ms (B20000) to prevent buffer under-runs and M20 minimum feedrate
 // M205 -  advanced settings:  minimum travel speed S=while printing T=travel only,  B=minimum segment time X= maximum xy jerk, Z=maximum Z jerk, E=maximum E jerk
-// M206 - set additional homeing offset
+// M206 - set additional homing offset
 // M207 - set retract length S[positive mm] F[feedrate mm/min] Z[additional zlift/hop], stays in mm regardless of M200 setting
-// M208 - set recover=unretract length S[positive mm surplus to the M207 S*] F[feedrate mm/min]
+// M208 - set recover=unretract length S[positive mm surplus to the M207 S*] F[feedrate mm/sec]
 // M209 - S<1=true/0=false> enable automatic retract detect if the slicer did not support G10/11: every normal extrude-only move will be classified as retract depending on the direction.
 // M218 - set hotend offset (in mm): T<extruder_number> X<offset_on_X> Y<offset_on_Y>
 // M220 S<factor in percent>- set speed factor override percentage
 // M240 - Trigger a camera to take a photograph
 // M250 - Set LCD contrast C<contrast value> (value 0..63)
 // M280 - set servo position absolute. P: servo index, S: angle or microseconds
-// M300 - Play beepsound S<frequency Hz> P<duration ms>
+// M300 - Play beep sound S<frequency Hz> P<duration ms>
 // M301 - Set PID parameters P I and D
 // M302 - Allow cold extrudes, or set the minimum extrude S<temperature>.
 // M303 - PID relay autotune S<temperature> sets the target temperature. (default target temperature = 150C)
 // M400 - Finish all moves
 // M401 - Lower z-probe if present
 // M402 - Raise z-probe if present
-// M500 - stores paramters in EEPROM
+// M500 - stores parameters in EEPROM
 // M501 - reads parameters from EEPROM (if you need reset them after you changed them temporarily).
 // M502 - reverts to the default "factory settings".  You still need to store them in EEPROM afterwards if you want to.
-// M503 - print the current settings (from memory not from eeprom)
+// M503 - print the current settings (from memory not from EEPROM)
 // M540 - Use S[0|1] to enable or disable the stop SD card print on endstop hit (requires ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED)
 // M600 - Pause for filament change X[pos] Y[pos] Z[relative lift] E[initial retract] L[later retract distance for removal]
-// M666 - set delta endstop adjustemnt
+// M666 - set delta endstop adjustment
 // M605 - Set dual x-carriage movement mode: S<mode> [ X<duplication x-offset> R<duplication temp offset> ]
 // M907 - Set digital trimpot motor current using axis codes.
 // M908 - Control digital trimpot directly.
 
 
 //===========================================================================
-//=============================private variables=============================
+//=============================Private Variables=============================
 //===========================================================================
 const char axis_codes[NUM_AXIS] = {'X', 'Y', 'Z', 'E'};
 static float destination[NUM_AXIS] = {  0.0, 0.0, 0.0, 0.0};
 static char serial_char;
 static int serial_count = 0;
 static boolean comment_mode = false;
-static char *strchr_pointer; // just a pointer to find chars in the cmd string like X, Y, Z, E, etc
+static char *strchr_pointer; // just a pointer to find chars in the command string like X, Y, Z, E, etc
 
 const int sensitive_pins[] = SENSITIVE_PINS; // Sensitive pin list for M42
 
 bool target_direction;
 
 //===========================================================================
-//=============================ROUTINES=============================
+//=============================Routines======================================
 //===========================================================================
 
 void get_arc_coordinates();
 {
   if(buflen < BUFSIZE)
   {
-    //this is dangerous if a mixing of serial and this happsens
+    //this is dangerous if a mixing of serial and this happens
     strcpy(&(cmdbuffer[bufindw][0]),cmd);
     SERIAL_ECHO_START;
     SERIAL_ECHOPGM("enqueing \"");
 {
   if(buflen < BUFSIZE)
   {
-    //this is dangerous if a mixing of serial and this happsens
+    //this is dangerous if a mixing of serial and this happens
     strcpy_P(&(cmdbuffer[bufindw][0]),cmd);
     SERIAL_ECHO_START;
     SERIAL_ECHOPGM("enqueing \"");
     return;
   }
 
-  //'#' stops reading from sd to the buffer prematurely, so procedural macro calls are possible
-  // if it occures, stop_buffering is triggered and the buffer is ran dry.
-  // this character _can_ occure in serial com, due to checksums. however, no checksums are used in sd printing
+  //'#' stops reading from SD to the buffer prematurely, so procedural macro calls are possible
+  // if it occurs, stop_buffering is triggered and the buffer is ran dry.
+  // this character _can_ occur in serial com, due to checksums. however, no checksums are used in SD printing
 
   static bool stop_buffering=false;
   if(buflen==0) stop_buffering=false;

Marlin/qr_solve.cpp

 
   Discussion:
 
-    DQRLSS must be preceeded by a call to DQRANK.
+    DQRLSS must be preceded by a call to DQRANK.
 
     The system is to be solved is
       A * X = B
     linear system.
 
     Output, double RSD[M], the residual, B - A*X.  RSD may
-    overwite B.
+    overwrite B.
 
     Input, int JPVT[N], the pivot information from DQRANK.
     Columns JPVT[0], ..., JPVT[KR-1] of the original matrix are linearly
     can be replaced by dummy variables in the calling program.
     To save storage, the user may in some cases use the same
     array for different parameters in the calling sequence.  A
-    frequently occuring example is when one wishes to compute
+    frequently occurring example is when one wishes to compute
     any of B, RSD, or AB and does not need Y or QTY.  In this
     case one may identify Y, QTY, and one of B, RSD, or AB, while
     providing separate arrays for anything else that is to be