Overwrite cura settings file.

Added a basic settings tab to the cura config menu. Cura Ini files are reloaded when the selection changes.
Added an overwrite button to settings tabs which updates the selected cura ini file.
Fixed cura refresh trigger.

The cura refresh trigger is run after the cura config path changed and when a configuration is clicked in the select box.
Only show the settings tabs when a configuration is present.