This allows PID_FUNCTIONAL_RANGE to use a maximum duty cycle higher
than PID_MAX. This is useful for powerful heaters to heat quickly in
bang-bang mode, but use a lower duty cycle that is easier to stabilize
in PID mode.

Definition for the graphic LCD are already in it, they will not harm the
configuration as they are only defined constants

The extruder offset can be specified in the configuration
file or adjusted on the fly using the "M218 T# X# Y#" command.
The EEPROM support is not yet merged in.
The "T#" command can take option "F#" that specifies the feedrate
at which the printing head should be re-positioned. If not
specified the re-positioning move is not preformed immediately,
but the coordinates are adjusted for the printer to properly
position the head when the next movement happens.

This change makes the choice of serial port configurable so that
wireless capability can be easily added by connecting Bluetooth modules
(such as BlueSmirf or JY-MCU) to the expansion port pins.

fixes #246
Added statements to set the limit switch positions to the maximum travel if homing in the positive direction as well as bed center at (0,0) if defined.
Relocated code based on feedback.

Added statements to set the limit switch positions to the maximum travel if homing in the positive direction as well as bed center at (0,0) if defined.

Conflicts:

	Marlin/Configuration.h

motor current and microstepping pins.

HOME_POS is now always where the endstop is and can be outside the limits.
The limits are now defined by MIN_POS and MAX_POS rather than HOME_POS and MAX_LENGTH.
The Z is axis now homed first if direction is away from the bed.

Saguinololu limit pins change from MIN to MAX according to the homing direction.

Turning off the protection might be beneficial to those who want to do fast and long reversals.

Changed SLOWDOWN. IF this does not work ok OLD_SLOWDOWN is the old algo.

Moved the PID_dT in the Ki and Kd calculation from the configuration.h to temperature.cpp

+ Removed most explicit pathnames, use the standard make "VPATH" to let
make find the files for itself.

+ Added a "hardware variant" variable that allows compiging Sanguino and
Gen7 as well as "generic" arduino.

+ Allows overriding the MOTHERBOARD define from the Makefile

+ Removed the 'preprocessor' bit that wasn't needed, now just "include" the
files that are needed, since it allows gcc to show the right file/line
when displaying error/warnings.

+ Uses gcc's own dependency generator to generate the .d files, and
and include these instead of self-patching the makefile

Signed-off-by: Michel Pollet <buserror@gmail.com>