Have dedicated Editor.closeDocument and Editor.closeSession
methods to correspond to openDocument and openSession.
Remove unused EditorSession.close method, not sure what it was
used for.
Merge pull request #182 from adityab/edit-close

Have dedicated Editor.closeDocument and Editor.closeSession
In OperationTransformMatrix.js move all utility methods before the real transformation methods
Extend OT matrix with methods for op "ApplyDirectStyling"
Make directTextStyler no longer optional, now that it works also in collab mode
Add TransformerTests (to test directly resulting opspecs, not execution consistency)

Useful for ApplyDirectStyling vs. ApplyDirectStyling, as that in the current
simple implementation will result in inconsistent DOMs (e.g. names of automatic styles)