audio_sink and video_sink leakage fixed

https://bugzilla.gnome.org/show_bug.cgi?id=730010
gst-play: Free playlist_file string if only printing the version
alsasink: pass correct error to g_strerror

The error we get is a negated errno.

While there, fix a couple typos in messages.
playsink: Always take the playsink lock when adding or removing pad probes

Otherwise we might end up inside the callback without having stored
the probe id... then try to remove that probe (not!) from the callback
and wait forever for the pad to unblock.
rtspconnection: Add read source on write socket.

Add a read source on write socket when lost tunnel.
To be able to detect when clint closes get channel.

This is already done in gst_rtsp_source_dispatch_write but
only when the queue is empty.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=730368
dmabuf: share the mapping with shared copies of the memory

With lots of shared memory instances (e.g. created by a RTP payloader) the
overhead of duplicating the file descriptor and creating extra mappings is
significant. To avoid this, the parent memory maps the whole region and the
shared copies just reuse the same mapping.

https://bugzilla.gnome.org/show_bug.cgi?id=730441
rtsp-transport: clarify port usage

Comment in the docs what the client_port and server_port fields are used
for in TCP mode (if the application wants to set those values).
video: Fix broken comparison in unit test

libs/video.c:540:50: error: comparison of constant 2 with boolean expression is always false
      [-Werror,-Wtautological-constant-out-of-range-compare]
            && !GST_VIDEO_INFO_N_PLANES (&vinfo) > 2) {
               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~
video: And check comparison for real
Automatic update of common submodule

From 211fa5f to 1f5d3c3
Update .po files
Release 1.3.2
Back to development
tools: play: use cubic volume factor when adjusting volume

This is more natural and better-suited for a playback application.