Implementation of AvalonEdit which overwrites the old text editor.
Adds line numbers to the EditControl. Introduces 'show_line_numbers' config parameter.
Improvements in config loading.
Added additional configs to AvalonEdit.
 - @DanPristupov I have made this way to prevent reimplementing configuration changed event in every tab
Added wrapping setting
Bumping AvalonEdit version to 5.0.2 (stable)
Merge branch 'AvalonEdit-overwrite' into develop

Conflicts:
	SuperbEdit.Base/Config.cs
	SuperbEdit.TextEditor/ViewModels/TextEditorViewModel.cs
	SuperbEdit/ViewModels/FallbackTabViewModel.cs