Fix usage of icon provider and fix a small attribute error bug if you're not using QCOdeEdit but QPlainTextEdit
Fix another attribute error
Fix visual bug with fold trigger

Improves the logic for adding/removing folded block decoration (boxes): this is now done in the paintEvent. This change let you fold blocks without using the Folding panel, just set the fold state to True using TextBlockHelper!
Merge branch 'master' into feature/filesystem_treeview