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

- The default serial baud rate of 115200
- The regular RigitBot bed size 254mm/248mm/254mm
- Single stock extruder
- Stock termistors for extruder and hotbed
- Stock Min X/Y/Z stops. Max stops not connected
- Stock 32 teth tooleys (stock axis steps)
- No auto bed leveling
- No screen

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

- `SD_DETECT_PIN` replaces `SDCARDDETECT`
- `SD_DETECT_INVERTED` replaces `SDCARDDETECTINVERTED`
- Revise the description of `SD_DETECT_INVERTED`
- Add a note about the override of `SD_DETECT_INVERTED` in
`Conditionals.h`

- Rename the pin so it can be tested with `PIN_EXISTS`
- Fix some incorrect tests for `SDCARDDETECT`

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.

instead of 1000.  Else we get errors with times over 32 seconds.