For consistency with other pins, allowing use of `PIN_EXISTS` macro.

Apply `ENABLED` / `DISABLED` macros to files needing only a small
number of changes.

Apply `ENABLED` / `DISABLED` macros to EEPROM-related files.

Apply `ENABLED` / `DISABLED` macros to planner files.

Apply `ENABLED` / `DISABLED` macros to temperature-related files.

Apply `ENABLED` / `DISABLED` macros to stepper-related files.

Apply `ENABLED` / `DISABLED` macros to LCD-related files.

Apply `ENABLED` / `DISABLED` / `HAS_SERVOS` macros to pins files.

Apply `ENABLED` / `DISABLED` macros to language-related files.

- The contents of EEPROM include filament diameters even with
Volumetric disabled. This change makes `M503` display the full
volumetric settings so that playing back the output of `M503 S0` will
fully restore them.

Just the minimal changes to qr_solve.cpp and .h to get rid of malloc() and free().

Saves about 656 bytes of progmem (library-code)
and 22 bytes for static variables.

Should use exactly the same amount of stack as it did before on the heap.