it's disabled by default

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

Fixed an error where SDCARDDETECTINVERTED was being defined/undefined
improperly

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

- 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`

This addresses comments in #1956 and #1079. In particular, this is useful
when both endstops are stationary on a CoreXY system, and the Y axis needs
to be homed before the X so the flags are aligned.

With these changes the output of `M503 S0` is all you need to restore
the EEPROM. Building on this it is straightforward to save and restore
the EEPROM state using the SD card or external GCode file.

- Added `M145` to set “heatup states” for the LCD menu
- Added `M420` to toggle Mesh Bed Leveling
- Added `M421` to set a single Mesh coordinate
- Extended `Config_PrintSettings` with added M codes
- Cleaned up some comments here and there

- Sections in all `Configuration_adv.h`
- Recognize JAPANESE/WESTERN/CYRILLIC options
- Better capturing of comments for tooltips

some people are starting to ask why homing is so slow. this is the old standard hard-coded value.

Z_DUAL_ENDSTOPS is a feature to enable the use of 2 endstops for both Z
steppers - Let's call them Z stepper and Z2 stepper.
That way the machine is capable to align the bed during home, since both
Z steppers are homed.
There is also an implementation of M666 (software endstops adjustment)
to this feature.
After Z homing, this adjustment is applied to just one of the steppers
in order to align the bed.
One just need to home the Z axis and measure the distance difference
between both Z axis and apply the math: Z adjust = Z - Z2.
If the Z stepper axis is closer to the bed, the measure Z > Z2 (yes, it
is.. think about it) and the Z adjust would be positive.
Play a little bit with small adjustments (0.5mm) and check the
behaviour.
The M119 (endstops report) will start reporting the Z2 Endstop as well.

- `Conditionals.h` is included twice, setting LCD values the first time

- Add `Conditionals.h` with calculated configuration values
- Add `SanityCheck.h` with checks for configuration errors
- Remove equivalent code from all configurations
- Move error checks from some sources to `SanityCheck.h` also
- Fix initialization of count_direction in stepper.cpp

- Also update base configs

- Both TMC, L6470 and pin-driven drivers work.
- All can be mixed and matched as needed.

This define is not used.

Small changes (and formatting to confuse the diff’er) which first
allows DOGLCD and LCD_PROGRESS_BAR to be enabled in tandem, then a
#warning (rather than error) that the extra progress bar / message
options don’t apply to graphical displays at this time. This leaves
open perhaps combining the progress bar and message area in some future
(or forked custom) graphical LCD display arrangement (at which time the
relevant variables may be moved into ultralcd.cpp with externs in
ultralcd.h). I also added a conditional error that the progress bar and
the filament display may not work well together.

- Fixed issue when BAL area probing is shorter than it should be for
grid probing
- Warning when BAL activated with Delta Kinematics
- Fix XY_TRAVEL_SPEED when homing Z axis

For legacy boards it’s better if this option is disabled.