globals: Improve config troubleshooting support

More context in issue jschuh#39

start_end: Speed up START_PRINT

* Skip parking, etc. when heaters are already at target.
* Added parameter to skip Z rehoming when bed hits temp.

globals: Fix issue jschuh#38

globals: Add default bed surface

Avoids a potential misconfig (and fixes bug jschuh#34).

filament: Fix issue jschuh#31

pause_resume_cancel: Fix issue jschuh#28