Fix a number of other qdoc issues.

* Several places needed the forward class declaration hack
* Missing/wrong minor version numbers on imports
* A few typos
* Any number of attempts to work around qdoc
* A few missing docs
* Tweaked soundeffect docs

Change-Id: I3c2ab998a11cbb0956712e0423e01fdb70f5bfff
Reviewed-by: Peter Yard <peter.yard@nokia.com>
Reviewed-by: Angus Cummings <angus.cummings@nokia.com>
Reviewed-by: Jonas Rabbe <jonas.rabbe@gmail.com>

src/multimedia/controls/qmediaavailabilitycontrol.h

@@ -52,6 +52,9 @@ QT_BEGIN_NAMESPACE
 
 QT_MODULE(Multimedia)
 
+// Required for QDoc workaround
+class QString;
+
 class Q_MULTIMEDIA_EXPORT QMediaAvailabilityControl : public QMediaControl
 {
     Q_OBJECT