GstMessage is now a boxed type.

extracting the structure requires using gst_message_get_structure.
One side effect is that returns a const pointer, so I had to modify things
slightly to keep the const-ness.
gst_message_new_duration was replaced with gst_message_new_duration_changed

(At least apparently) Also the new function determins format and duration
on its own, so those parameters were removed.
AsyncDoneMessage now needs a running time parameter.
gst_element_make_from_uri now takes a GError parameter

Pass in the error pointer and convert it to a C++ exception.
gst_uri_handler_get_protocols returns a const gchar * const *

do a bit of type modification to match signature.
gst_uri_handler_set_uri now takes a GError **

pass it in and throw a C++ error if needed.
Deal with a mysterious import error.
gst_query_get_structure returns a const pointer.
gst_query_parse_formats_length and gst_query_parse_formats_nth were renamed.
Add some #includes to deal with missing declarations
gst_buffer_try_new_and_alloc was removed.

The additional functionality was moved into gst_buffer_new_and_alloc
replace Buffer::timeStamp with two functions.

They now have two different timestamps, one for presentation,
one for decoding.