[1.1.x] XON/XOFF serial handshake (for faster transfers to SD)

[1.1.x] Fix DUAL_X_CARRIAGE manual move

Addressing #7745

XON/XOFF changes

[1.1.x] Fix broken M600 resume_print

[1.1.x] Option to disallow motion before homing

Forgot to update examples configurations. Done now

Added new configuration to inhibit XYZ movements when home is not done

Expected behaviour: while (auto)extruding the new filament, the nozzle should not move. It should move (from filament replacement position to printing position) only after the user has confirmed the successful filament replacement and extrusion.

Actual behaviour: while (auto)extruding the new filament, the nozzle moves from filament replacement position back to printing position.
So the extrusion step is mixed with the movement required to go back to the printing position.

The provided code seems to be working but probably a better fix is required.

Based on #7792 by @tcm0116

[1.1.x] Show leveling status on character LCD

[1.1.x] User menu return-to-status option

Based on #7769

Melzi fixes

Fixed typo where ST7920_DELAY_2 was being #defined after a check for #ifndef ST7920_DELAY_3

Sanity Check for LCD_FOR_MELZI  would fail with "Please select no more than one LCD controller option" any time #define LCD_FOR_MELZI was enabled in Configuration.h, even if there were no other LCD options enabled.

[1.1.x] Fix G3D_PANEL encoder steps, babystep label

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.

As pointed out by @marcio-ao in #7638

More featureful CR-10 configurations

* matrix names update

* symplified names

* new angle normalization

* ABC

* axis

* least squares

* recalc_delta_settings

* endstop_adj

* 0p

* bug

Fix caselight compile issues

Added option for graphical overlay for Z-offset (Resubmission of #7350 and #7586)

M111: no args reports current flags