WMF: allow to load media whose content doesn't match its file extension.

This also allows to play streams without providing a MIME type.

Task-number: QTBUG-33631
Task-number: QTBUG-33518
Change-Id: Ia106592cb5ed0a0f7ede6308dc8e2c12cf4e63b1
Reviewed-by: Christian Stromme <christian.stromme@digia.com>
WMF: allow to set a qrc file name as source of a QAudioDecoder.

Task-number: QTBUG-33518
Change-Id: I01d8a1fa7b9a1c3ea2af9de6033dff2773cd6ace
Reviewed-by: Christian Stromme <christian.stromme@digia.com>