aggregator: Unref the taglist in GstAggregator::stop()
videoaggregator: Unmap and free GstVideoFrames as needed after conversion and errors
openh264enc: make denoise work

https://bugzilla.gnome.org/show_bug.cgi?id=737894
videoparser: comment unused GST_BASE_PARSE_FRAME_FLAG_PARSING

GST_BASE_PARSE_FRAME_FLAG_PARSING value is wrong, and the same flag is
not being used presently. Hence changing the value and commenting it out.
This needs to be included in baseparse.h later on

https://bugzilla.gnome.org/show_bug.cgi?id=737411
curlsmtpsink: Email with multipart content-type should end with a final boundary

    Add final boundary for each of the sending out emails from smtpsink.

https://bugzilla.gnome.org/show_bug.cgi?id=736134
openh264: Use a MARGINAL rank for the encoder and decoder

They work but for now we prefer others until these are extensively tested.
aggregator: Store segment when seeked in READY for later use
aggregator: set future seqnum before propagating the seek event.

So the seqnum is properly set for the following events.
aggregator: Query seeking when a seek failed to see if it was expected

And do not worry if seeking failed on a stream that is not seekable
aggregator: Add a streaming lock so to secure flush start action

Without a lock that is taken in FLUSH_START we had a rare race where we
end up aggregating a buffer that was before the whole FLUSH_START/STOP
dance. That could lead to very wrong behaviour in subclasses.
aggregator: Set seqnum only when segments are received.
videoaggregator: Make sure not to unref a NULL pointer
videoaggregator: Do not wrongly set the aggregator.segment

The aggregator.segment is not to be initialized by the subclasses but
by the aggregator itself. Moreover, initializing it on start would make
us loose the information coming from the initial seek.
audiomixer: Port to GstAggregator

https://bugzilla.gnome.org/show_bug.cgi?id=737183

Co-Authored by: Mathieu Duponchelle <mathieu.duponchelle@opencreed.com>
audiomixer: Set the sinkpad segments basetime after seeking

Otherwise stream offset and running time comparison will not be
correct, leading to segfaults after seeks
audiomixer: Handle seek event in READY state
aggregator: Replace GMainContext with GAsyncQueue (v2)

The previous implementation kept accumulating GSources,
slowing down the iteration and leaking memory.

Instead of trying to fix the main context flushing, replace
it with a GAsyncQueue which is simple to flush and has
less overhead.

https://bugzilla.gnome.org/show_bug.cgi?id=736782
curlsmtpsink: Set CURLOPT_UPLOAD to 1 to not use VRFY and other unneeded commands

Fixes the sink with SMTP servers that disable VRFY for spam protection.

http://sourceforge.net/p/curl/bugs/1389/
glcolrconvert: fix YUY2 download

- The shader was outputing the wrong values compared with raw
  videotestsrc.
- deal with the texture edge properly.
- properly sample the 2x1 rectangle for the u and v values
- don't double sample the y value
glcolorconvert: fix UYVY download green screen