Provde a GUI option to disable requiring CTRL to dnd text

This adds a GUI checkbox per profile to enable/disable requiring the
CTRL key to drag-n-drop text.
The default is to require the CTRL key as before.

Thanks to Scott Kitterman (kde@kitterman.com) for patch.

BUG: 165923
REVIEW: 105423
FIXED-IN: 4.10