Editors: Remove BaseTextEditorWidget::setBaseTextDocument

First step in never changing the text document after construction,
because that is actually not really supported.
Second step will be to fix that for the editor duplicate() methods too.

Change-Id: I3d112ba0895e7ee7ac6dd8ae2318f0de7d2cebc9
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>
ProFileEditor: Remove unused factory variable

Change-Id: Ifa20cc17675dfce1da9b087ee2e9b2ecdb3d8f22
Reviewed-by: Daniel Teske <daniel.teske@digia.com>