Revert "BaseTextEditWidget: Forward everything with ControlModifier to QPTE"

Lead to annoying behavior that pressing any disabled shortcut with control
modifier would lead to unwanted characters in the editor.
This reverts commit c1ff105a0ccffd7b1e96e6c5070ae857c1b7df4c.

Change-Id: If61e52be9f11cabeafb46f5d71b901b4eab8e169
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Reviewed-by: Daniel Teske <daniel.teske@digia.com>