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

Disallowed the Z_PROBE_OFFSET_RANGE_MAX to be greater than zero.

 - Remove the forced activation of SDSUPPORT, I guess people may use the ZUM
3D board and not the LCD module.
 - Fixed the tab issue within boards.h file.

Added support for BQ ZUM Mega 3D board and stock Hephestos 2 thermistor.