Initial SAV MkI (RepRap CloneWars board) integration.

Included support for BT dongle on AT90USB boards.
Added LCD Shift Register LCD control
Included support for RepRap Clone Wars project board (SAV MKI).
Fix servo control for Melzi
Corrected LCD only error

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

Added conditional compilation.
Add (correct) missing pin definitions for Y2

I tested this and it works.
Add UUID support to M115 responses.
Added BT support on AT90USB devices

Added AT90USB device BT connectivity support using second UART.
If you have a switch on suicide pin, this is useful if you want to
start another print with suicide feature after a print without
suicide...
Implement M226 - GCode Initiated Pause

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
Merge pull request #635 from dbenamy/Marlin_v1

Add (correct) missing pin definitions for Y2
Merge pull request #636 from PrintToPeer/Marlin_v1

Add UUID support to M115 responses.
Merge pull request #637 from justuswilhelm/Marlin_v1

Fix servo control for Melzi v2.0
Merge pull request #640 from fmalpartida/SAV-MkI

Added support for BT on AT90USB devices, corrected LCD bug, added new board and LCD
Merge pull request #641 from hugokernel/master

M80 - ATX Power On related modification
Merge pull request #647 from shaggythesheep/newfeature-M226

Implement M226 - GCode Initiated Pause
Fixed compile errors from bad commits.
Added HEATERS_PARALLEL (Request from reifsnyderb)
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.
Changed slow buttons behavior.
Added new board for those of us with sanguinololu boards with ceramic resonators
Allow heaters to stay full On when PWM=127

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.
Z Axis Safe Homing when using Z Probe

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.