Fix Print preset being dirty at load time
Fix compilation under 5.20 (untested). #2109
Fix regression in Quick Slice and Slice to SVG
Strip all png images to avoid libpng warning
Merge pull request #2135 from hroncok/iccp

Strip all png images to avoid libpng warning
Refactored OptionsGroup class for cleaner OOP model and cleaner event model
Enable/disable GUI controls according to the others in order to guide the user through option dependency
Minor adjustment in tooltip
Initialize controls status when loading cut window
Fixed background processing with multiple worker threads
Fixed regression causing variable layer heights to be ignored. #2136

Conflicts:

	xs/xsp/my.map
Enable min_fan_speed and disable_fan_first_layers when fan_always_on is checked