Minor improvements for encoder configuration, LCD entry for PSU controll and thermistor pins on RAMPS

Revert "Made numbering of heat bed thermistor more logical as D8 is bed, D9 is Extruder 2 and D10 is Extruder 1, so T0 should be E1, T1 E1 and T2 bed to be sequential as MOSFET-Outputs"

This reverts commit b7eadb9f.

Added new board

Z and Y dual stepper drivers error

if you try to enable Z_DUAL_STEPPER_DRIVERS the error "You cannot have dual drivers for both Y and Z" shows even if you don't have defined Y_DUAL_STEPPER_DRIVERS and don't let you compile the firmware

to solve this problem i change this line:

#ifdef Z_DUAL_STEPPER_DRIVERS && Y_DUAL_STEPPER_DRIVERS

to:

#if defined (Z_DUAL_STEPPER_DRIVERS) && defined (Y_DUAL_STEPPER_DRIVERS)

now the error only show if you define both Z_DUAL_STEPPER_DRIVERS and Y_DUAL_STEPPER_DRIVERS

Added posibility to set ENCODER_STEPS_PER_MENU_ITEM in Configuration.h like ENCODER_PULSES_PER_STEP as it depends on it for usability

Made numbering of heat bed thermistor more logical as D8 is bed, D9 is Extruder 2 and D10 is Extruder 1, so T0 should be E1, T1 E1 and T2 bed to be sequential as MOSFET-Outputs

Added support for Cheaptronic v1 electronic

In some cases the Bed Heater FET heats up more then stepper drivers, so
this change add the bed monitoring to the controller fan. As soon as the
bed heater is turned on, the controller fan will run as well.

Recommended for those who are using the Z Probe for Z Homing (as
Z-Endstop)

This feature has two changes:

1) Allow user to choose where the Z Probe will touch the bed when homing
all axis together (G28) by setting below defines:

Z_SAFE_HOMING_X_POINT
Z_SAFE_HOMING_Y_POINT

2) Prevents the user to perform Z Axis Homing when the Z Probe is
outsite bed.

In previous version, even with PWM = 127, the system turns the FET off
and then on in the next cycle. This bevavior may increase the FET heat
dissipation.
It was fixed keeping the FET always On when PWM=127.

This allows a hot end with two heaters and a FET for each heater. This is useful if the FET is not capable of heating two heaters.

Implement M226 - GCode Initiated Pause

M80 - ATX Power On related modification

Added support for BT on AT90USB devices, corrected LCD bug, added new board and LCD

Fix servo control for Melzi v2.0

Add UUID support to M115 responses.

Add (correct) missing pin definitions for Y2

Implemented M226 as described here:
http://reprap.org/wiki/G-code#M226:_Gcode_Initiated_Pause

Waits for pin to be become either HIGH, LOW or the inverse of what it
was before. Allows printing to pause until user interaction

start another print with suicide feature after a print without
suicide...

Added AT90USB device BT connectivity support using second UART.

I tested this and it works.

If only an LCD is defined and no menu or keyboard defined, there is a
compilation error.

Added conditional compilation.

Made instructions more clear.

Not sure what happened to my last commit so this includes that one + reordering the steps.

Included support for BT dongle on AT90USB boards.
Added LCD Shift Register LCD control
Included support for RepRap Clone Wars project board (SAV MKI).

PS_ON configurable boot state

Allows the user to select wheter or not the PSU should be turned on or
kept in standby when marlin boots

Make G11 not horribly broken

since it can occure in comments.