`AddMissingOverride` can handle "abstract override" combination

Fixes #1002227
Update `AddMissingOverride` to actual version of scala-refactoring
Fix `AddMissingOverride` for constructor parameter

Fixes #1002225
Check if save action is enabled before it is created

Creating a save action when it is not enabled is a waste of resources
and also has the problem for compiler driven save actions that an
exception can be thrown when the builder is interrupted by a save event.
Move save action references to `SaveActionExtensions` companion object
Handle nested values in `AddReturnTypeToPublicSymbols`
Add no return type to refinement types

Adding the full refinement type leads to ugly code and removing the
refinement could load to compilation errors.
Add ignored test about unimplemented behavior in `AddMissingOverrideTest`
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
Add possibility to update cursor to auto edits

This adds a new `Change` object to pass an updated cursor position from
an auto edit to the logic that applies it.

This also adds some syntax sugar for auto edits to operate on the input.

The return type of the auto edit has changed to an `Option` because it
is possible that an auto edit can not be applied. Previously the input
change object had to be returned to describe this situation but
returning an `Option` makes more sense.
Add test suite for auto edits
Add tests for `ConvertToUnicode` auto edit
Enable `ConvertToUnicode` on pasted symbols

Auto edits should be able to react on everything that is pasted into
the editor. If for example the "=>" symbol is pasted, the auto edit can
now handle such an input and convert it to its unicode counterpart.