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
glcolorconvert: fix planar YUV download

- sample the u and v planes properly
- output the correctly scaled u and v planes for different chroma block sizes
glcolorconvert: output why we cannot convert a buffer
dashdemux: push a time segment when restarting streaming

This should inform demuxers/decoders downstream that the stream is
about to start from a new position and they should flush accordingly

https://bugzilla.gnome.org/show_bug.cgi?id=736319
dashdemux: mark first buffer as discont after restarting a download task

Mark first buffer as discont after restarting a download task, so
downstream can reset its state to properly handle the new fragment.

Related issue: https://bugzilla.gnome.org/show_bug.cgi?id=736318

https://bugzilla.gnome.org/show_bug.cgi?id=736319
tsdemux: do not discard on discont if PES start

If a discontinuity in the stream is detected, data is discarded until
a new PES starts. If the first packet after the discontinuity is also
the start of a PES, there is no reason to discard the packets.

https://bugzilla.gnome.org/show_bug.cgi?id=737569
gltransformation: requires graphene 1.0.0
fluiddec: don't crash on 0-sized input buffers

https://bugzilla.gnome.org/show_bug.cgi?id=737658
androidmedia: Fix calculation of the frame size for COLOR_FormatYUV420Planar

https://bugzilla.gnome.org/show_bug.cgi?id=734156
vc1parse: unref caps when it is empty in renegotiate()

https://bugzilla.gnome.org/show_bug.cgi?id=737724
aggregator: Unref the taglist in GstAggregator::stop()
videoaggregator: Unmap and free GstVideoFrames as needed after conversion and errors
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/
h265parse: expose parsed profile, tier and level to downstream

https://bugzilla.gnome.org/show_bug.cgi?id=732239
h264parse: expose parsed profile and level to downstream

Set parsed profile and level in src caps.

https://bugzilla.gnome.org/show_bug.cgi?id=732239
vtenc: Port to the real VideoToolbox API instead of using our dlopen() wrapper

It's a public framework since a long time.
vtdec: Fix compiler warnings

values of type 'OSStatus' should not be used as format arguments; add an explicit cast to 'int' instead [-Wformat]
vtenc: Use correct instance struct size
vtenc: Port to GstVideoEncoder base class