Z_PROBE_ENDSTOP Pin for Azteeg X3 Pro

Minor optimizations

Compiling error temperature.cpp with multiple extruders defined

Just a simple #ifdef Z_PROBE_ENDSTOP to define the pin for it. Also has
a couple commented lines for switching Z_MIN_PIN if needed.

It wouldn't compile because of this line in temperature.cpp it turns out
it was just a stray ( that didn't line up with the previous lines so I
just made it in line with the rest and it compiled fine.

Fix: thermal_runaway_protection triggered by target temperature increase

Add PIDTEMPBED to EEPROM

Fixed README typos

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