If Marlin is blocking the serial input or command queue for any length
of time (for example more than 2 seconds), it needs to send a message
to serial out to inform the host that it is busy. Marlin should only
send these messages out when busy, and preferably not when trying to
print formatted output.

follow-up the commit 7326d63ce0
update Configration_adv.h of Hephestos2
delete unnecessary spaces

rebased
corrected spelling
changed to #elif for error

Still with MIN_Z_HEIGHT_FOR_HOMING but con be done with (folder wide) search-replace when we have a better name.

update old comments
update or delete deprecated definitions
complement forgotten updates
adjust spacing
some cosmetic changes

As suggested by @max-pau in #3073 - #3074

files.

Redo of #2939 rebased against RCBugFix

Renamed `WARN_REDUCED_ACCURACY` to `DISABLE_REDUCED_ACCURACY_WARNING`

Changed the condition for blinking from
```
#if ENABLED(WARN_REDUCED_ACCURACY)
```
to
```
#if DISABLED(DISABLE_REDUCED_ACCURACY_WARNING)
```

This formalizes the dependency of MANUAL_BED_LEVELING on
MESH_BED_LEVELING

- Include aligned comment about new SDSUPPORT behavior

Instead of changing SDEXTRASLOW variable to a slower speed,  the new
SDULTRASLOW is used for rigidbot panel.

Instead of changing SDEXTRASLOW variable to a slower speed,  the new
SDULTRASLOW is used for rigidbot panel.

• Removing trailing whitespace
• Adjusting indention for better readability
• Removing duplicated entries

Analog to https://github.com/MarlinFirmware/MarlinDev/pull/250 by
@RicardoGA

Restore the Babystep Multiplicator functionality and now it's available
for X/Y/Z

For now Z_MIN_PROBE_REPEATABILITY_TEST is not possible for DELTA or SCARA
configurations.
This PR comments the feature out, where it is commented in by default.

Add SDEXTRASLOW which runs the SD card at SPI_QUARTER_SPEED. Quarter speed is needed for RIGIDBOT_PANEL

As noted in #130 allen key probe stow rate is based on homing rates,
but homing rates were left out of most delta configs. This unifies the
XYZ homing rates and applies the unified rates to allen key movements.