Various documentation fixes ported from 4.8
Selected documentation fixes for qtbase from 4.8 commit
40fb4750910e23d3e7128ca8e0f1c5920b05bd5a
Task-number: QTBUG-8625
Task-number: QTBUG-19808
Task-number: QTBUG-1231
Task-number: QTBUG-21073
Task-number: QTBUG-8939
Task-number: QTBUG-20399
Task-number: QTBUG-20944
Task-number: QTBUG-22095
Task-number: QTBUG-11278
Task-number: QTBUG-15653
Change-Id: Ia4f59fce7c85f04b6da953a3988f705d9d9a658a
Reviewed-by: Casper van Donderen <casper.vandonderen@nokia.com>