Merge pull request #224 from skyluc/issue/API-PresentationCompiler

Adapts to PresentationCompiler API changes
Updates code to use sdt.core methods

The methods of sdt.editor have been moved in sdt.core
Modifies the way to get an editor from a viewer

The editor is stored in the TextViewer using getData/setData.
Remove the sdt.editor code
Adapts to completion proposal change
Fixes the compilation problem, but breaks Scala hovers in play template

editors
Merge pull request #225 from skyluc/issue/API-move-delete-editor

Removes the sdt.editor plugin
Moves to sdt version of syntax Category
Adapts to generic syntax colouring preference page
Adapts to ScalaSyntaxClass cleanup
Adapts to the new syntax parsing API
Adapts to RegionUtils API changes