Typo fixes in comments in existing code.

Z_DUAL_ENDSTOPS is a feature to enable the use of 2 endstops for both Z
steppers - Let's call them Z stepper and Z2 stepper.
That way the machine is capable to align the bed during home, since both
Z steppers are homed.
There is also an implementation of M666 (software endstops adjustment)
to this feature.
After Z homing, this adjustment is applied to just one of the steppers
in order to align the bed.
One just need to home the Z axis and measure the distance difference
between both Z axis and apply the math: Z adjust = Z - Z2.
If the Z stepper axis is closer to the bed, the measure Z > Z2 (yes, it
is.. think about it) and the Z adjust would be positive.
Play a little bit with small adjustments (0.5mm) and check the
behaviour.
The M119 (endstops report) will start reporting the Z2 Endstop as well.

- Add BIT and TEST macros
- Add _APPLY_ macros to stepper.cpp to help with consolidation
- Consolidate code in stepper.cpp using macros
- Apply standards in stepper.cpp
- Use >= 0 instead of > -1 as a better semantic
- Replace DUAL_Y_CARRIAGE with Y_DUAL_STEPPER_DRIVERS

- Also apply cleanup for #1514

Also fix analogInputToDigitalPin so it uses proper C hex notation

#1405 includes some changes to pins.h for a 4th extruder. This commit
applies those changes. It also deals with a possible problem with
SENSITIVE_PINS.

Hopefully this is helpful to organization and future expansion….

Also fix analogInputToDigitalPin so it uses proper C hex notation

Hopefully this is helpful to organization and future expansion….

#1405 includes some changes to pins.h for a 4th extruder. This commit
applies those changes. It also deals with a possible problem with
SENSITIVE_PINS.

Hopefully this is helpful to organization and future expansion….

Pins 2 and 3 are probably general-use pins, since the filament sensor
uses pin 2.

Changes to temperature.cpp from Ultimaker fork, intended to address
#1226 and #1227

Changes to temperature.cpp from Ultimaker fork, intended to address
#1226 and #1227

## Add: Board for Vellemann K8200 (derived from 3Drag)

* Boards.h: updated comment for board 3Drag - K8200 removed
* Boards.h: added `BOARD_K8200` with ID 78

* language.h.: machine name and firmware URL for new board

* pins.h: added `K8200` to any `#if` with `3Drag` and corresponding
comments

When a melzi board and a full gfx are both selected, the build fails
blaming for some missing defines.

This is a fix for the issue: now my configuration works.

Backported from Printrbot branch, allows the fan to work correctly.

Updated pins reference and servo support.

cross referenced between Rambo 1.1, 1.2, and 1.3

Somehow the pin definitions for the MAX6675 Slave Select/Chip Select got changed back to the hardware SPI SS/CS.  
Pin 49 cannot be used as that is used by the SD card socket to detect if an SD card is present.
Pin 53 is the Hardware SPI SS, which is dedicated, nicely, to the SD card SS and therefore cannot be used as the MAX6675 SS
Pin 66 is in Aux2 port adjacent to the Hardware SPI interface port on RAMPS 1.4, and is currently not used for anything.

Tested for SAV MKI and SAV 3D LCD on lewihe.

Added boards.h which contains defines for all the board numbers, plus
some shorthand macros for less typing.

Added boards.h which contains defines for all the board numbers, plus
some shorthand macros for less typing.

	modified:   Marlin/Configuration.h
	modified:   Marlin/pins.h

This feature allows the printer to read the filament diameter
automatically and adjust the printer in real time.  Added code to read
an analog voltage that represents a filament diameter measurement.  This
measurement is delayed in a ring buffer to compensate for sensors that
are a distance away from the extruder.  The measurement is used to
adjust the volumetric_multiplier for the extruder.  Some additional g
codes (M404, M405, M406, M407) are used to set parameters and turn
on/off the control. g code M221 is updated.  Pins for RAMPS1.4, RAMBO,
and Printrboard are identified for analog input.  The configuration file
is updated with relevant user parameters.

I have added the pin set for the leapfrog and the support of dual Y and Z

Leapfrog board added to the pin list

Techzone Monotronics support, ignoring the tip manager and using fan connector as on Sprinter FW
TODO: Add support for tipmanager