Screen: Add additional lossless codecs for GStreamer video writing/recording.

Add support for ‘y4menc’ for near lossless YUV4MPEG raw writeout. This
is only near lossless for grayscale (+/-1 unit error), more lossy for
rgb (+/-6 units due to chroma subsampling), but can be processed by
most oss tools. Essentially this stores raw yuv data in a container,
uncompressed, only chroma spatial subsampled.

‘ffenc_sgi’ is another codec: It RLE encodes images into image/x-sgi
format and dumps them into a stream of images via multipart muxer. The
format is completely lossless for 1, 3, 4 channels, and can compress
well for some pictures, but such files can only be read by Psychtoolbox
or other GStreamer/FFmpeg based tools which provide multipartdemux
support. Also the “stream of images” loses any framerate information,
so playback will always assume a fixed 25 fps and seeking in such a
“movie” is not possible. This format might be good for compressed
storage during live recording, but will need transcoding to make actual
use of data most of the time..

Add a new specialFlag1 setting 256 to Screen(‘Openmovie’) which allows
to disable the deinterlacer, as use of it (even as pure no-op
passthrough!) can incur color format conversions which prevent
lossless’ly stored 8 bit grayscale data from being decoded lossless -
lossy on decoding instead of encoding!

-> Screen for 64-Bit Matlab on OSX rebuilt and tested.
-> LosslessMovieWritingTest.m updated. Now can display min/max error
and error distribution histogram if lossy conversion is detected.