Redo of #2939 rebased against RCBugFix

Introduce additional variable axis_homed to replace axix_known_position
when the coordinate display should indicate the axis is not homed.
This is to distinguish between "not homed" and "inexact position possible
because stepper was disabled".

# Conflicts:
#	Marlin/ultralcd_implementation_hitachi_HD44780.h
solved

Make the output of M105 more similar to Repetier.
Make the text-print pert of M105 an extra function to make it reusable. `print_heaterstates()`
Use `print_heaterstates()` in M019, M190 and M303

Keep "astyled" reformatting

With the introduction of the #if ENABLED(…)

reads better than

* Fix a couple of renames omission and macro expansion errors.

- For some reason it’s easy to forget what BT stands for, but it
doesn’t need an abbreviation.

The compiler may be able to optimize if it knows an array won’t be
changing.

Note that newer versions of the IDE can still
be made to support compilation for the older boards.

replace extruder_multiply with extruder_multiplier
like feedrate_multiplier or volumetric_multiplier

Makes the output on the LCD adjustable.

- For better encapsulation add inlines for each prepare_move type
- Move controllerFan vars inside the function as statics
- Some formatting cleanup
- Rename `ClearToSend` as `ok_to_send`

this PR replaces some bools with one char. this will safe 3 bytes and should also be sometimes a little bit faster.

- Add `M111` as a standard option to set the debug level
- Implement `DEBUG_ECHO` in `process_commands`
- Other debug levels (e.g., `DEBUG_DRYRUN`) need more work

- Include the current Z when raising the axis after and between probing
- Add `sync_plan_position_delta` for parity with `sync_plan_position`
- Clean up and clarify `M48`, `dock_sled`, and others

This rolls back to commit 06f767d608.

Fix for #1460.

Seems to work with only one extruder. Can't test this myself with more.