linuxmakeitoctave3: Switch to GStreamer-1.x backend and libfreenect-0.5 build.

-> Switch build of Screen for Octave on Linux to use of GStreamer-1.x.
-> Switch build of PsychKinectCore for Octave on Linux to use of
   libfreenect-0.5 from GitHub (until ND is providing official freenect 0.5).

-> PsychKinectCore.mex for 64-Bit Octave on Linux rebuilt and tested.
-> Old PsychKinectCore would have also worked against libfreenect-0.5 by simply
   setting a symlink from libfreenect-0.1.x --> libfreenect-0.5
-> Some code reformatting in PsychKinect.c - more to do.
GStreamer-1.x: Fix some compiler warnings about incomplete mapinfo initializers.

-> Needs to be fixed properly by upstream GStreamer. For now we just suppress
   the (apparently new) compiler warning.
Screen/GStreamer-1.x: Improve video source probing for GStreamer < 1.4

- Use enumeration by probing for Video4Linux2 devices and DV devices.
  Probing this way is fast and works reliably for Video4Linux2 sources
  and likely (to be tested) with DV-1394 and HDV-1394 sources.

- Some code reformatting.

- Fix crash for pixelformat 6: We were calulating size of the videobuffer
  wrong for avg. intensity calculation (pixelcount * 2 instead of * 1).
  This caused segfault when overrunning the input buffer during read.

-> Screen for 64-Bit Octave on Linux rebuilt and tested with iSight and
   USB cameras so far. Tests on Firewire pending.

-> Application/Selection of ROI, different pixelformats and selection of
   video capture resolution [0 0 w h] works on Linux, only fails on OSX,
   so apparently not a PTB bug, but some bug of GStreamer-1.4.0 on OSX or
   of Apples underlying capture api's.
Merge branch 'master' of https://github.com/kleinerm/Psychtoolbox-3