Merge BaseTextEditorWidget::editorDocument() and ::baseTextDocument()

Doesn't really make sense to have the additional IDocument *editorDocument()
method.

Change-Id: I0a7420eb1afaa76f63c3f7e9c4b373acf624ffb9
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Move document -> code assist connect to CodeAssistant::configure

Change-Id: I6124c12a269093fbd54cbbbb47b4d7f15ffaae2f
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
QmlJsEditor: remove empty function

Change-Id: Ifc694394ebde336de0b7d1492dedf840c9e9a8dd
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>