We don't have any ways to store them in a persitant way anyway,
for example the content will disappear if the managed mini object
is unreffed and later the same native instance is used again in
managed code.
Also fix indention everywhere and change code to use Gst.MiniObject.GetObject()
instead of GLib.Opaque.GetOpaque().
It's currently not possible to implement or use GInterfaces on mini objects
but apart from that this should be a great improvement, especially new
mini object classes can be defined in C# now.
