Also clean up some trailing spaces in a few other sources

it's disabled by default

#defining something just to define something else doesn’t
make sense

If you want SDCARDDETECTINVERTED, just define it yourself.

If the previous code was intended to define, undefined and then again define the term, that code is improper.

* all Configuration_adv.h: Add #define FAN_MIN_PWM for slow fan stopping
issue
* for K8200: uncommented with tested (and working) values

Updated all the example Configuration.h files for the new display type.

Minor wording correction.

- Make thermal protection for all hotends and/or bed into simple
switches
- Now enable `WATCH_TEMP_PERIOD` when `THERMAL_PROTECTION_HOTENDS` is
enabled
- Move detailed thermal parameters to `Configuration_adv.h`
- Add sanity checks to warn about old configurations
- Change `WATCH_TEMP_PERIOD` to seconds instead of milliseconds

in all Configurations.

- Add “Level Bed” menu item for auto bed leveling
- Hide the option if homing has not been done yet
- Arrange the Prepare submenu more logically (?)
- Add documentation comments, some white-space
- Apply some coding standards here and there
- Move old encoder multiplier debug option to `ultralcd.cpp`