Axis would only move when homing.
Bug introduced in 91841d75c9.
Fixes #6956, fixes #7050 and fixes #7291

Connected as described at http://printrbot.com/shop/led-strip/

Based on patch by Kelly Anderson <kelly@xilka.com> at
http://www.xilka.com/printrbot/marlin/1.1.4/20170707/

Without this...  The LSF won't work because none of the sampled points
in this code block get added.

We can save more and a pile of RAM by eleminating the eqnBVector and
EqnAMatrix arrays next.

Fixes #7250

Addressing #7227

Sends pre-defined string as action command when printer is kill.

Probing with the effector in the printing area, but an eccentric probe (e.g. allen key) outside it but still touching the bed gives meaninfull information for calibration. Since calibration is most accurate when probing as close to the towers as possible the testing was way to restrictive hence this fix.