Adapts to generic syntax colouring preference page
Adapts to ScalaSyntaxClass cleanup
Adapts to the new syntax parsing API
Merge pull request #200 from skyluc/issue/API-Syntax

Updates for new Syntax API
Add a document setup and file buffer-based document provider.

This allows the hovers to retrieve the compilation unit, and it is the
way documents are handled elsewhere (sdt.core, JDT, play2).
Adapt to changes in master.
Add an ‘F3’ action to navigate to definition.

Closes #167.