Implemented synchronization message output for NanoDLP printers (nanodlp.com).
If optional feature is enabled in `Configuration_adv.h`, Marlin will ouput "Z_move_comp" string to serial after completing any G0/G1 Z-axis movements. This feature patched on previous versions(1.0) is used by NanoDLP to synchronize Z-axis movement with projector exposure in DLP stereolithography printers.

* Fix thermal protection documentation.

Even before the recent thermal protection changes, the documentation of
the thermal protection feature in the config files did not match the
implementation.  I fixed the documentation and reconciled the M303
implementation with the documentation.

* Applied documentation changes to sample config files

* Renamed hysteresis to watch_temp_increase

* Added gcodes back into documentation.

* Initial conflict resolution

All previous items resolved:
- Use of ELAPSED() on timer code
- Switch to use of defer_return_to_status=true as much as possible
- Update & Clean Up of Max7219 routines

* Resolve non-SD case in ultralcd.cpp

Based on #7637 by @marcio-ao

Ideally, it should be calculated based on Z steps per unit so that each
babystep corresponds to around 0.025mm. Smaller than this is largely
insignificant for typical layer heights.

* Add MAX7219_DEBUG to Travis CI testing

* Tweak config and use standard pin naming for MAX7219_DEBUG

* MAX7219: Apply coding standards, use macros, etc.

* Make code work...

* Add Max7219 LED Matrix Debug Support

The Max7219 8x8 LED Matrix's are very helpful for debugging new code.
And for that matter, just trying to maximize printer settings without
causing stuttering.

The displays are very inexpensive (under $2.00 with shipping) and
provide a lot of help when trying to debug complicated code.

* Try to keep Makefile up to date.

Add a parameter to enable/disable audible user script feedback

Add more details as requested in #7198

Sends pre-defined string as action command when printer is kill.

* [New Feature] I2C position encoder support

I plan to continue improving/cleaning this up, as there areas that need work.

* let the cleanups begin.

* progress

* more progress

* comments, rename files, etc.

* clean

* Cleanups per thinkyhead

* a few more cleanups

* cleanups, bugfixes, etc.

* remove unnecessary passes_test(), additional cleanups/optimizations

* cleanups

* misc.

* Fix up I2CPEM.init() and a few other things.

* organize, fix, rename, etc.

* more optimization

* a few more tweaks