Implement AVR Platform

20x4 map integration.    Also some minor changes to the UBL Menu layout.     Both 20x4 LCD's and Graphical LCD panels should have similar functionality now.

- Fix: When "100.0" changes to "99.0" the LCD shows "199.0"
- Use 2 rows if needed on character LCD, (allowing longer labels…
Germany, et. al.)
- Known issue: A certain length label combined with a certain value
drawing function could, for example, display 99.0 on 1 line, but 100.0
on two lines. Workaround would be to pass a nominal value size argument.

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add test to Travis

Original Mesh Bed Leveling replacement put at top of UBL Menu Options to
help facilitate the removal of the Original Mesh Bed Leveling.

Radar display (and control) of the UBL Interactive Mesh Editing.

* Remove ADVANCED_PAUSE_FEATURE requirement for PROBING_HEATERS_OFF

* Add HEATER_IDLE_HANDLER conditional

* Save up to 94 bytes of RAM on 20x4 LCD Display machines

Moved the custom screen characters out of RAM into Program Memory.  With
SD-Card support and the Progress Bar enabled, this saves 94 bytes of RAM
memory.

This was tested using the example_configurations/FolgerTech-i3-2020
files.  So a couple small changes to those files snuck into this Pull
Request.

Probably...  We can find similar savings in the Graphics LCD code it we
comb through it.   And if so...  That is the place we really need to
save RAM memory!

* Tidy up white space and indentation

* Unify M600 and M125 pause features
* Cleanup per thinkyhead's comments
* Rename filament_change_menu_response to advanced_pause_menu_response
* Include HAS_BED_PROBE in QUIET_PROBING
* Update gMax example file
* is_idle() is out of scope without the braces
* Convert FT-i3-2020 to Advance Pause names...
* Allow pause even if not printing

Fixes #6426