gst-discoverer: Support non-ASCII tags

By calling setlocale() to get us multi-byte/UTF-8 support.

https://bugzilla.gnome.org/show_bug.cgi?id=723164
gst-play: Support non-ASCII tags

By calling setlocale() to get us multi-byte/UTF-8 support.

https://bugzilla.gnome.org/show_bug.cgi?id=723164
videotestsrc: ensure having caps when setting the buffer pool config

It happens if downstream does not propose a buffer pool.
GST_DEBUG=2 gst-launch-1.0 videotestsrc ! fakesink

https://bugzilla.gnome.org/show_bug.cgi?id=723271
docs: doc fixes for audio library

Add sections docs for audiometa. Fix sections docs for audiochannels. Remove old
mixerutil section.
tagdemux: Forward TIME seeks upstream too, maybe upstream can handle that

https://bugzilla.gnome.org/show_bug.cgi?id=723597
jsseek: Add missing HAVE_X check

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=723507
check: add some more checks

Add header and payload length check in case of CSRCs.

See https://bugzilla.gnome.org/show_bug.cgi?id=723196
basetextoverlay: use correct segment for text

video time uses the 'segment' and the text time should use
the 'text_segment'.

If different segments are used for video and text it would
lead to out of sync video/subtitles.