Use generic byte blobs for formats. We currently use them to store
gstreamer caps but we could also use them to exchange serialized
GVariants if we want.
Make properties a variant dictionary
Avoid using the autogenerated object manager because it does not
emit signals in the right context in all cases. Use our own proxy
and make our own proxy objects when they appear.
Make it possible to get a previously created proxy object or wait when
it is still being constructed.
Add introspect API
Move private things to private.h
Use custom main-context for the context, and ensure everything is called
from the custom main-context. does not work well with glib proxy signals
yet.
Work with custom mainloop in the gstreamer element.
