QInputMethod better describes what the class is about, input methods
in general, be they panels or just composing input from key events.
Compatability headers added for old name. Not bulletproof but should be
enough to get transition done.
Change-Id: Iefde6e7ccb1ec4a3b226cef3469089e751c60fc1
Reviewed-by: Joona Petrell <joona.t.petrell@nokia.com>
