Moved CreateAssemblyModelFromFile utility methods from ClassBrowserPad to separate ModelFactoryExtensions class (as extension methods).
Better synchronization of checkboxes in "Insert Ctor" snippet dialog.
Introduced "Convert interface to abstract class" context action.
Added text of error messages shown by ModelFactoryExtensions to resources, updated resource files.
When list of AddIns (installed or in repository) gets updated, view is trying to restore the previous item selection.
Added "Run" context menu item for custom assemblies in ClassBrowser.
ClassBrowser: "Add to workspace" context menu command for Debugger modules.
Add basic rich-text support to AvalonEdit.
Introduce 'RichText' class and use it in new output pad API.
Replace HighlightedInlineBuilder with RichTextModel.
Fix RichTextModel.UpdateOffsets()
Set e.Handled = true in SharpTreeView.OnKeyDown()
ModelCollectionEvent: allow removing event handlers from within an event handler
Use NullSafeSimpleModelCollection where possible
Move ModelCollectionChangedEvent to its own file.
Make RichTextWriter and derived classes internal; they're not necessary for using RichText/RichTextModel anymore.

If no new usecase comes up, these classes can be deleted (except maybe for HtmlRichTextWriter).
Merge remote-tracking branch 'origin/newNR' into classbrowser
Localized some menu items added with ClassBrowser and updated string resources.