There are some quite tricky ones which are hardly translateable.
Maybe @Sebastianv650 can review this

Fixes #6426

Fixes #6445

Also...   The memory corruption issue may be fixed.   The GCC compiler
was inlining static functions and this caused the G29() stack frame to
become much larger than the AVR could handle.

More consistent with M665 where C-value is allowed as well, then
normalized

* relocated ubl state to config. store:
 * removed a number of ubl state variables and padding which were largely unused - saved 58 bytes of both SRAM and EEPROM;
 * modified ubl sanity_check - no longer checks removed state variables that were otherwise unused, where checking didn't seem to accomplish anything, ultimately;
 * removed pre_initialized state, saving 64 bytes of SRAM;
 * removed automatic saving of UBL state after UBL activation/deactivation;
* consolidated multiple GRID_MAX_POINTS_X/Y to 'Global Leveling' section of EEPROM;
* minor update to G29 Sx notes/instructions;
* renamed mesh load and save parameter to 'slot' from 'm' for clarity;

fix maximum mesh_index_ array size at 16 (15+1);

Add polish font for GLCD displays only.
HD44780 work properly without polish character.
Update language_pl.h.

Adding '7-point' tower angle correction calibration

- adding Cn 5, 6 and 7

and getting rid off verbose level 3 and configuration_adv settings

- Making M665 compatible with repetier (see
http://reprap.org/wiki/G_code#M665:_Set_delta_configuration)

- M665 B also sets the radius for manual calibration menu

- Converting tower ajustment definitions to arrays - tower angle
corrections compatible with Esher 3D wizzard

- Only tower angles need to be adjustable with M665 and stored to EEPROM
- tower radius and diag rod can be adjusted in the FW only with #define

https://github.com/MarlinFirmware/Marlin/commit/5e9726530f
ac1b9437c2

- use volatile for registers
- avoid implicit casts