Sorry for not having realized someone (me) redefined not existing servo pinns to -1, some lines above.
This is a simple error - not a feature.

This is the easiest way to make button pin testing consistent without
renaming all the button pins. Just make a macro especially for testing
if button pins are set, since they are named consistently in the pins
files.

Following up on #3231

Aim: Test probes in update_endstops only when activated

Changes:
Configurations
 Add define for FIX_MOUNTED_PROBE to handle the situation where formerly ENDSTOPS_ONLY_FOR_HOMING had to be set, or lowering the nozzle below Z_PROBE_OFFSET_FROM_EXTRUDER could give an "endstop hit" message.
 Add define for Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN to indicate a common situation, that we have a probe but it is connected to an endstop pin
 Add some comments
 Shift some entries to have related things together.

Conditionals.h
 We have a probe (HAS_Z_MIN_PROBE) if one of the pins is defined AND one of the probes is defined.

SanityCheck.h
 Add some tests if the probe is connected and if we have defined a probe.

stepper.cpp
 Changes to test the probe only when it is deployed (z_probe_is_active).
 Test update_endstops() when the probe is deployed.

MarlinMain.cpp
 a. set and reset z_probe_is_active in deploy_z_probe(), stow_z_probe() and dock_sled()
 b. set and reset z_probe_is_active in the case a z-servo is moved to a defined position. The only remaining unhandled servo move is in M280 where we do not end in a defined position. If you want to handle a probe use M401/402
 c. skip deploying/stowing when already deployed/stowed in the dedicated deploy/stow functions.
 d. Handle the new FIX_MOUNTED_PROBE in parallel to a servo driven probe/endstop.

 To do: In another PR. handle all probes in deploy/stow_z_probe.
 Sort out SERVO_LEVELING vs. HAS_SERVO_ENDSTOPS.

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.

 - 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.

Redo of #2939 rebased against RCBugFix

Keep "astyled" reformatting

As noted in #133 you can’t disable `SDSUPPORT` with `MAKRPANEL`,
`PANEL_ONE`, `MINIPANEL`, or `ULTIPANEL`. This patch makes it possible
to disable `SDSUPPORT` on these controllers and then disables it by
default.

Users of these controllers will now need to enable `SDSUPPORT` in their
configurations as others currently do.

With the introduction of the #if ENABLED(…)

reads better than

* Fix a couple of renames omission and macro expansion errors.

Currently we use the probe exclusively as a device to find the build platform(bed).
For the currently supported setups this means, we use it as a additional min-endstop.
A triggered when not deployed probe disturbs the homing process for max-endstops.

Rename ENDSTOPPULLUP_ZPROBE to ENDSTOPPULLUP_ZMIN_PROBE
Rename Z_PROBE_ENDSTOP_INVERTING to Z_MIN_PROBE_ENDSTOP_INVERTING
Rename Z_PROBE_ENDSTOP to Z_MIN_PROBE_ENDSTOP
Rename DISABLE_Z_PROBE_ENDSTOP to DISABLE_Z_MIN_PROBE_ENDSTOP
Rename Z_PROBE_REPEATABILITY_TEST to Z_MIN_PROBE_REPEATABILITY_TEST
Rename Z_PROBE_ENDSTOP to Z_MIN_PROBE_ENDSTOP
Adjust comments accordingly
Remove Z_MAX  check for the probe in update_endstops().

Using an delta related idea of @clefranc from #61,
extended to the general change for all setups.

Tested with Prusa i3, max-z-endstop and permanently triggered z-probe.
Worked for @clefranc's delta.