issue 968 for dev branch

try, try again.

If 'OK' is garbled on sending PC won't receive it.  Both machines will
wait on each other forever.  This resends OK if nothing is heard from PC
for a while to avoid this bad case.

temp runaway: proper cast to prevent any overflow.

Define analogInputToDigitalPin only if needed

Added further tests to Travis CI config

Fix for cant compile when REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER ...

Readd .travis.yml

Added .gitignore back into repo

Move scripts and documentation to subfolders

The compiler does not support comparing float values: "error: floating constant in preprocessor expression"
The loss in X/Y precision shouldn't matter for Z probes, as most microswitches or inductive sensors are larger than 1mm square anyway.

Due to the fix for #1248, X and Y probe offsets must not be floats.

Add Filament menu and add Filament/Retract settings to config store.

Fix typo, PID_BED_POWER -> MAX_BED_POWER

temperature.cpp: Fix typo of MAX_BED_PID to MAX_BED_POWER.

The compiler does not support comparing float values: "error: floating constant in preprocessor expression"
The loss in X/Y precision shouldn't matter for Z probes, as most microswitches or inductive sensors are larger than 1mm square anyway.

MAX6675 Slave Select pin 

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.