dvbsrc: smarten up tuning logic

* Drop remaining sleep() logic in favor of polling
* Use best guess delivery system if none is set
* Make tuning/locking timeout configurable
* Add signals for tuning start, done and fail
* Drop gst_dvbsrc_frontend_status(). It was used only
  for signal LOCK checking. This is now part of the
  tuning/locking loop
* Break up frontend configuration and tuning
  on separate functions

Plus:

* Add some more useful DEBUG/TRACE messages
* Move over misplaced DVB API message
* Fix wrong comment for default DVB buffer size (http://linuxtv.org/downloads/v4l-dvb-apis/dmx_fcalls.html#DMX_SET_BUFFER_SIZE)

This patch builds up on previous work done by
Fabrizio (Misto) Milo <mistobaan@gmail.com>

https://bugzilla.gnome.org/show_bug.cgi?id=641204
dvbbasebin: proxy new props/signals from dvbsrc

Proxy tuning start/done/fail signals and tuning-timeout
property.

https://bugzilla.gnome.org/show_bug.cgi?id=641204
dvbbasebin: fix dvbsrc signal proxying

https://bugzilla.gnome.org/show_bug.cgi?id=641204
dvb/cam*: use g_strerror and other few nits
opencv: make the plugin compile with all 2.4.x versions

https://bugzilla.gnome.org/show_bug.cgi?id=730141
motioncells: use standard macro for boolean

https://bugzilla.gnome.org/show_bug.cgi?id=730141
motioncells: make framedrop work at 30 fps too

https://bugzilla.gnome.org/show_bug.cgi?id=730141
motioncells: improve logging

https://bugzilla.gnome.org/show_bug.cgi?id=730141
dvbbasebin: add prop setup code for guint64

Needed since we are now proxying tuning-timeout
from dvbsrc.
dvbbasebin: better error handling in case tsparse is missing

https://bugzilla.gnome.org/show_bug.cgi?id=730641
mpeg2enc: increase max. allowed value for bitrate property

For DVD the limit is around 10Mbit/s, but for e.g. ATSC
it could be much higher.
mpegts: Remove unneeded NULL check

Allocating those structures is done in all code paths leading there

CID #1219860
CID #1219861
CID #1219862
CID #1219863
CID #1219864
glcontext: Handle (unlikely) NULL return of gl->GetString (GL_VERSION) more gracefully

CID 1219858
mpegdemux: avoid crashing in pathological case

(Identical to commit 612cdeec80da95b12f9fad928419c7de2be20d68 which
was for resindvd)

When we'd see an unknown stream type, then a SDDS stream.
Then we'd get to the end of the switch with a NULL temp stream
pointer, and dereference it.

Coverity 1139708
speed: make position query able to convert bytes to time

(same as 744c58d71b21475d2edd5b9334e277cfa4c53260 but for the
position query)

It was only querying in time, but then trying to use dead bytes
to time conversion code.

Coverity 1139677
androidmedia: Fix crashes when loading the plugin in a standalone application on Android >= 4.4

Check if libnativehelper is loaded in the process and if
it has these awful wrappers for JNI_CreateJavaVM and
JNI_GetCreatedJavaVMs that crash the app if you don't
create a JniInvocation instance first. If it isn't we
just fail here and don't initialize anything.

See this code for reference:
https://android.googlesource.com/platform/libnativehelper/+/master/JniInvocation.cpp
androidmedia: Clear the exception before trying to call Java methods to convert it to a string
androidmedia: Actually print the stacktrace into the error string
shmsink: Allocate enough memory to do alignment

https://bugzilla.gnome.org/show_bug.cgi?id=731093
gdp: Fail gracefully if event can't be parsed

https://bugzilla.gnome.org/show_bug.cgi?id=731093