becaue it is over-restrictive and superseeded by the now working tests
if the probe-recktangle can be reached. See iss#2366

Sign flipped with #2167.
See also comments
https://github.com/MarlinFirmware/Marlin/issues/2040#issuecomment-118568355
and following.

- Also fix a bug in `M600` where `Z_MAX_ENDSTOP_INVERTING` is being
used as the index into the `destination[AxisEnum]` array.

here the other two occurences of `Z_PROBE_OFFSET_FROM_EXTRUDER` are
replaced with `zprobe_zoffset`.

verified via 1.0.2 tag that compiles by multiple people,
credit for the fix goes to paulusjacobus for the initial find and
sniffle for the correction so M851 works.

in Development

BOARD_ULTIMAKER was not the default any more
- sed failed to change the board
- RAMPS_EFB has no second extruder
- ...
- Added test for bed

Rebased.