TextEditor: Start moving data from *EditorWidget to *Editor

Goal is to consolidate "controller" related data in the *Editor hierarchy.
This patch introduces temporary "cross-Private" accessors dd() to
keep the patches small.

First item moved is the AutoCompleter, a glimps at long term benefits
is the simplification in the JavaEditorWidget which is now essentially
a BaseTextEditorWidget, only containing the still-wrong createEditor().
But that can only be move if the *Editors are self-contained, i.e.
keep data themselves, not indirectly through the *EditorWidgets.

Change-Id: Ia0ab90f0322bb17ac20458e6581069eed30acbaf
Reviewed-by: Christian Stenger <christian.stenger@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>