- `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`
- Reduce calls to millis()
- General cleanup of manage_heaters
- General cleanup of pid autotune
- Formatting here & there
- Macros to clean up and shrink ISR code (reduced by ~364 lines)
