dsengine.dll plugin for camera does not play nicely with rest. If used, video won't work (dsengine.dll / DirectShow)

To use a camera or webcam on Windows the only option available currently is to use the dsengine.dll mediaservice plugin. However there are several issues with it.

1) In the Qt 5.0.0 binary distribution the dsengine.dll is missing completely. Therefore cameras cannot be used at all. See https://bugreports.qt-project.org/browse/QTBUG-28047

2) A self compiled dsengine.dll shows the following issues:

2.1) It has a hard dependency on Qt5MultimediaWidgets.dll and therefore a dependency on Qt5Widgets.dll and therefore requires the user to use QApplication instead of QGuiApplication. All of that shouldn't be required for QtQuick 2.0 apps.

2.2) It registers itself as mediaplayer before wmfengine.dll can do. Because of that video does not work anymore. Using the QML Video element gives: "The QMediaPlayer object does not have a valid service". A work-around to this issue is to rename "dsengine.dll" into "xdsengine.dll". Because of the renaming it is now loaded after the wmfengine.dll and thus video and camera can work at the same time.

I think this should get a high priority because currently nothing camera related can be used on Windows.