Add GUI controls for editor settings.
Add class to handle settings.
Add editor settings.
Add more settings (AutoIndent / TabIndents / IndentationsUseTabs).
Integrate with QSettings.
Update GUI to make options a bit clearer for the user.
Change settings handling to use Value objects.
#1119 Added missing slot to change tab key function
Merge pull request #1119 from openscad/scintilla-updates

Scintilla updates