Screen for 64-Bit Octave on Linux rebuilt on 14.04-LTS.
Screen: Bits of whitespace/indentation cleanup in GStreamer videocapture.

Prepares next commit.
Screen: Make video setting validation for GStreamer-Videocapture less fragile.

This failed if the engine was able to enumerate capture caps, but
not actually parsed the entries. Auto-detection failed with bogus
values like an image size of 1 x 1 pixel. Manual override failed due
to validation failure.

Long story short, this makes sure that auto-detection falls back
to waiting for the first preroll buffer and online negotiation if
it can't enumerate modes it can actually parse. This way we get
at least some useful video mode. Validation of manually specified
settings now just accepts any given setting if it can't meaningfully
validate.

Makes the Delock 61769 USB-2.0 video grabber work better.
Work better means, we can get it to grab and return video
with proper timing and resolution. I don't know if the video
is actually valid video, as i didn't have an analog camera
to actually connect, so i could only see the all-blue standby
image. To be tested properly next week with an actual camera...

-> Screen for 64-Bit Octave on Linux rebuilt and tested.