fix uref mismatch in helper_uref_stream
fix PTS in mp2v framer
fix PTS in h264 framer
more verbosity
allow to set dejitter divider
rework the API of upump_mgr and uclock helpers

Also fix PTS handling in avcodec_decode.
add need_uclock event
trickplay module to play at a given rate
make glxplay work at the stream framerate