caps no longer has a type member, use QGlib::Type::fromInstance to find type.

caps used to be a wrapped structure, but is now a MiniObject.
Several caps functions now return a pointer.

Update member variable with the returned value.
gst_pad_get_caps_reffed was removed

The recommendation to use gst_pad_query_caps. However that API
call doesn't return a writable caps. If that's needed
the suggestion is to use gst_caps_make_writeable
gst_pad_get_negotiated_caps was replaced with gst_pad_get_current_caps

I renamed the method from negotiatedCaps to currentCaps to match
the current Gstreamer API.
gst_pad_set_caps was deprecated. The replacement was to send a CAPS event.

To do that a CapsEvent class was added to the event classes defined
in event.h and global.h
gst_pad_set_blocked was removed.

The recommended replacement was to use gst_pad_add_probe. However
that is an asyncronous API, this solution is probably wrong in
that it doesn't provide a callback for the result.
gst_element_provide_clock was removed.

I'm hoping that the ClockPtr::wrap works correctly for a NULL return
value.
Replace several functions with ElementFactory::metadata.

Previously they had longName, klass, description, author, documentation
and iconName functions to retrieve specific metadata elements.