Deltabot settings and configuration adjustments.
Use X/Y/Z_MAX_PIN instead of X/Y/Z_MIN_PIN for top endstops on deltabot.
Enable QUICK_HOME for deltabot.
Add realtime delta geometry in Marlin_main.cpp.
Fix typo in MANUAL_HOME_POSITION (plural S missing) and reduce BLOCK_BUFFER_SIZE because 64 wasn't working for some reason.
Merged updates from Marlin_v1.
Fix home_all_axis to make QUICK_HOME work with Repetier-Host which sends G28 X0 Y0 Z0 instead of G28. Thanks to Matt Schoenholz for reporting this issue.
Fix typo (# missing before define).
{X,Y,Z}_{MIN,MAX}_POS are actually in Gcode coordinates.
Disable is now multi extruder compatible. M84 got a T option.
PID now per extruder. Fixed typo
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).
Implement automatic extruder/cold-end fan control based on temperature

This change allows fan outputs to automatically turn on/off when the
associated nozzle temperature of an extruder is above/below a threshold
temperature.
Multiple extruders can be assigned to the same pin in which case the fan
will turn on when any selected extruder is above the threshold.
It also makes the M42 command compatible with the M106/M107 command.
The majority of the logic in this change will be evaluated by the
compiler at build time (i.e, low code space requirements).