Fix probe height at G28 start

Latest upstream commits

Finish pin tests

fix feedrate for homing z

Latest upstream commits

Z_PROBE_ENDSTOP

Incorporating Build Numbers

Latest upstream commits

Fix typo in Marlin_main.cpp

max_feedrate is in mm/s. line_to_destination needs a feedrate in mm/min because there is feedrate/60.

Refer to http://git-scm.com/docs/gitignore
to see why this is appropriate

The automatic versioning system extracts a
build version number from the SCM system

That versioning information is written to the file
_Version.h, a file that is NOT preserved in the SCM.

If such a file will be present,
we include it here to utilize the parameters
that are defined therein.

related to current_position[Z_AXIS] and retract_zlift.

'+ =' -> '+='

Fix for #1786

- Add comments documenting `thermal_runaway_protection`
- Add an enum for the thermal runaway states
- Add macros for temperature helper functions
- Fix a glitch with the z probe sled in homeaxis

Catch unlikely but possible error and head crash when using
Z_PROBE_REPEATABILITY_TEST

Fix MIN&MAX temperatures again

old bump_divisor for cartesian/corexy-printer

is not used.

some people are starting to ask why homing is so slow. this is the old standard hard-coded value.

Conflicts:
	Marlin/Marlin_main.cpp

Added new - changed entries from Fix up LCD_PROGRESS_BAR

Fix homing and leveling

Added support for Atmega 1281 chip