Added LiquidCrystal_I2C library to ArduinoAddons
Added Config variables for activating I2C LCDs and setting type and address
Added I2C port expander support to HD44780
Added import of Wire Library to make I2C LCD support compilable
Made i2c mode wok with the hardware I am able to test (ywrobot  / sainsmart i2c LCD 2004)

Removed incorrect LiquidCrystal_I2C Library
Converge all I2C LCD branches (PANELOLU2, VIKI & PCF8575)

This includes refactoring the buttons code to remove a large amount of
non-pin dependent duplication from pins.h.
Fix Configuration.h file to not define LCDs be default.

Also fix compile time check in Marlin.pde
Attempt to address Bernhard's comments

Refactor configuration to try to make items clearer (what defines a
panel vs what is user changeable).
Support encoder click on PANELOLU2 being read through I2C

This change also handles the case where the pause/stop/restart button on
the VIKI is not used. Make LCD I2C buzz sound the same as the normal
buzz (300ms is too long for quick feedback).
Updated for LiquidTWI2 library version 1.2.3

The new version of the library means that PANELOLU no longer needs to be
defined in LiquidTWI.h (the library file can be used as is) and the new
version of the library also enables the buzzer on the Panucatt VIKI
panel.
Merge remote-tracking branch 'upstream/Marlin_v1' into Marlin_v1

Conflicts:
	Marlin/Marlin.pde
	Marlin/ultralcd.cpp
	Marlin/ultralcd_implementation_hitachi_HD44780.h
Add lcd_buzz function to ultralcd.h so that non-LCD code can make use of lcd's buzzer.

Argument order of lcd_buzz was set to mirror that on tone(). Change
default M300 frequency to something audible.
Make DOGLCD merge neater.
fix DEFAULT_AXIS_STEPS_PER_UNIT minor Z rounding error
Merge pull request #459 from martinxyz/fix-rounding-error

fix DEFAULT_AXIS_STEPS_PER_UNIT minor Z rounding error
Solved minor bug in controllerFan()

Extruder 2 was checked where extruder 1 should be checked.
Merge pull request #464 from arnoudja/Marlin_v1

Solved minor bug in controllerFan()
Replace the <= to < in the Command M907, M350 and M351.
The for loop for Axis count over the Array.
Add a break after M907
If CORE_XY is in use X and Y Axis had to be activated at the same time
Merge pull request #466 from midopple/Marlin_v1

BUG Fix in Commands M907,M350 and M351