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 defaults to configuration_adv.h
disable auto retract by default

This should make it safe to enable FWRETRACT by default, with
autoretract (which should now be fixed) only enabled by M209. FWRETRACT
should probably now default to enabled (to make G10/G11 and M207-209
available, without changing functionality when they are not used), but
I’ll save that for another pull request/discussion.
Added dutch to language.h
Fixed some messages where the text shown on the screen was more than 17 characters
Fixed small typo that would prevent compiling
Merge pull request #776 from whosawhatsis/fwretract

Fwretract fixes, cleanup
Revert "Fixed small typo that would prevent compiling"

This reverts commit 51ae4881ab0fea7f82fcf6d8266a5b53cd17e007.
Merge pull request #782 from marcovannoord/Marlin_v1

Added dutch to language.h
Use descriptive constants instead of numeric literals
Use descriptive constants, more
Prevent G29 without first homing in X and Y

If position is unknown, then G29 can be dangerous.
update comment
Merge pull request #794 from MissionSt/g29_requires_home

Prevent G29 without first homing in X and Y
Merge pull request #793 from MissionSt/use_axis_enums

Use constants instead of numeric literals
Merge branch 'Marlin_v1' into mendel90