Fix QTextInlineObject class documentation

Change-Id: I10ac533c1ba7a8003b59b1617af98afbdd4ed17f
Task-number: QTBUG-39784
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@theqtcompany.com>
Rename internal enum value to avoid clashing with Xlib

Change-Id: I4926d1f75ece220d28abf9f2e7081e41f0aaf339
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>
Reviewed-by: Martin Jansa <Martin.Jansa@gmail.com>