M200 implementation
Fixed math

This is why I wanted to sleep on the code I wrote while falling asleep
rather than immediately submitting a pull request.
Change diameter code to 'D'

For some reason I couldn’t find, using ’S’ causes the decimal to be
dropped, so 1.75 become 1.00.
minor code improvement for M200
Keep FWRETRACT values in terms of millimeters when using M200 for volumetric E units
use fwretract for this branch
correct feedrate units in comments for M207/M208
G10/G11 bugfixes

Previous version was broken by using G92 E0 between retract and recover.
better default FWRETRACT settings
fix logic reversal
Fix G10/G11 Z-lift
Fix autoretract

This takes the (now working) G10/G11 code and moves it to a function,
which is called by G10 and G11, and also called by G1 if autoretract is
enabled and a retract/recover move is detected.
Move fwretract settings to configuration_adv.h