Update needed for the Qt platform notes on Multimedia and Phonon

On http://doc.qt.nokia.com/4.7-snapshot/platform-notes-symbian.html#multimedia-and-phonon-support
we have some outdated documentation on "Multimedia and Phonon Support"

1. "In this release the support is experimental. Video playback may have flickering issues, "

We should be more concrete and update this to current issues as artefacts are visible only when video is resized, rotated or moved (including fullscreen switches). This doesn't generally prevent applications from using the library but they should know the limitations and not do resizing or moving of content once presented. Also this is issue is particularly a problem on S^1 devices and earlier, but Symbian^3 devices have artefacts visible when this is done. Gareth Stockwell commented that due to the way the windowing system works, these are unlikely to go away until we can render video to a texture; see QTMOBILITY-729 for the current status.

2. "support for (audio) effects and playback queueing is incomplete"

According to Gareth the audio effects are now supported and playlist handling should work also work correctly.

3. "The audio and video formats that Phonon supports depends on what support the platform provides for MMF. The emulator is known to have limited codec support."

The emulator codec limitations are still valid.

4. "In addition, there exists a backend for the Helix framework. However, due to it not shipping with Qt, its availability depends on the Symbian platform in use. If available, it is loaded in preference over the MMF plugin. If the Helix plugin fails to load, the MMF plugin, if present on the device, will be loaded instead."

From Qt 4.7.2 onward the MMF based backend is the one that is used by default (See QT-4427).

5. This section should also note of the other multimedia features on Qt and Qt mobility as the title is "Multimedia". Also the Qt Mobility documentation says that Qt Mobility Multimedia API is probably the preferred API to be used since Qt mobility documentation says it's multimedia API is replacing Phonon at a later stage in http://doc.qt.nokia.com/qtmobility/multimedia.html).

6. At http://doc.qt.nokia.com/qtmobility/qtmultimediakit.html
"QtMultimediaKit is a module containing the low level, low latency, Multimedia APIs which were introduced in Qt 4.6 and also includes the high level QtMultimedia <http://qt.nokia.com/doc/4.7/qtmultimedia.html> APIs which were introduced in Qt Mobility 1.0."

This latter is quite strange as it says Qt Multimedia was introduced in Qt mobility 1.0 but then refers to Qt 4.7 docs. It also says they are high-level APIs but then when user clicks on the link there the doc says:
"The QtMultimedia module provides low-level multimedia functionality".