Start implementing AutoEdits
Add preference page for auto edits
Add preference initializer for auto edits
Move common definitions to `SWTUtils`
Check if auto edit is enabled before it is executed
Add copy method and better apply method to `TextChange`

The apply method now creates the best fit text change object and not
only an `Replace` object.
The copy method considers forwards to this apply method to keep the
behavior.
Start implementing the `ConvertToUnicode` auto edit