Added option to invert Z axis controls
Added .g to the allowed extensions for file uploads
Changed renaming to sd filenames to also work properly with very short names (and names with more .) as at least Marlin seems to hiccup on something like "file.gco.gco"
Do not crash if SD card fails in firmware
Changed SD filename generation, made SD handling more reliable as a whole (cherry picked from commit 717ec041)
Merge remote-tracking branch 'upstream/devel' into devel

Conflicts:
	src/octoprint/util/comm.py