dmabuf: fix checking mmap flags

A simple '&' is not sufficiant. With mmapping_flags == PROT_READ and
prot == PROT_READ|PROT_WRITE the check produces the wrong result.
Change the check to make sure that prot is a subset of mmapping_flags.

https://bugzilla.gnome.org/show_bug.cgi?id=730559
decodebin: Do async-done on expose errors too
uridecodebin: Ignore missing-plugin messages unless all decodebins post one

When playing RTSP streams there will be one decodebin per stream. If some of
them fail because of a missing plugin we should not fail completely but play
the supported streams at least.

https://bugzilla.gnome.org/show_bug.cgi?id=730868
uridecodebin: Also catch CODEC_NOT_FOUND errors and delay them until all decodebins are done
tests: fix uninitialized variable use in video decoder test
vorbisenc: add missing va_end in variadic function

Coverity 1139944
theoraenc: Remove unneeded check

running timestamps are guaranteed to be positive and valid since the
GstVideoEncoder base class will clip incoming buffers

CID #1139797
video: avoid overflows when doing int operations for size

size is a gsize, so cast the operands to it to avoid overflows
and setting wrong value to the video size.

Includes tests.

https://bugzilla.gnome.org/show_bug.cgi?id=731195
videoscale: vs_image: strides are a gsize

The strides that are set from the GstVideoInfo structs are
a gsize. Using an int can cause overflows when dealing with large
enough images

https://bugzilla.gnome.org/show_bug.cgi?id=731195
appsrc: add send_event handler for flushing

Adds a send_event handling for allowing appsrc to flush its internal
data, allowing users to flush the pipeline without setting it to null.

https://bugzilla.gnome.org/show_bug.cgi?id=724231
docs: add navigation interface to docs
docs: add playsink element to documentation
docs: add streamsynchronizer to documentation
oggdemux: allow unset seek stop time in push mode
mikey: Fix Wall to NTP conversion

We are scaling from a unit in microseconds to a unit in ((1 << 32) per seconds).

We therefore scale the microseconds values by:

         value of a second in the target unit (1 << 32)
  --------------------------------------------------------------
  value of a second in the origin format (1 000 000 microsecond)
tcpserversrc: return FLOW_FLUSHING instead of an error when accept/select is canceled

Canceling the accept/select happens when the source is shut down. This is
not an error and the GST_FLOW_ERROR causes problems when only part of the
pipeline is shut down.

https://bugzilla.gnome.org/show_bug.cgi?id=731567
tcpclientsrc: return FLUSHING when select() is canceled

https://bugzilla.gnome.org/show_bug.cgi?id=731567
tcpserversrc: close the server socket after accepting a connection

g_socket_accept() is only called once for a server socket. So
keeping the socket open ist just confusing possible clients.

https://bugzilla.gnome.org/show_bug.cgi?id=731566
audiodecoder: Don't be too picky about the output frame counter

With most decoder libraries, and especially when accessing codecs via
OpenMAX or similar APIs, we don't have the ability to properly related
the output buffers to a number of input samples. And could e.g. get
a fractional number of input buffers decoded at a time.

Previously this would in the end lead to an error message and stopped
playback. Change it to a warning message instead and try to handle it
gracefully. In theory the subclass can now get timestamp tracking
wrong if it completely misuses the API, but if on average it behaves
correct (and gst-omx and others do) it will continue to work properly.

Also add a test for the new behaviour.

We don't change it in the encoder yet as that requires more internal logic
changes AFAIU and I'm not aware of a case where this was a problem so far.
po: Update translations