Screen: Add support for NVidia NV-E0 GeForce-600 gpu's.

Add detection logic to OSX PsychtoolboxKernelDriver so it can detect
and handle those GPU's, e.g., in the new MacBookPro Retina machines
with GeForce GT-650M.

Add experimental support to address up to 4 crtc's, as those Kepler
gpu's can drive up to 4 displays instead of only 2. This may or may not
work, fingers crossed.

Update installation instructions in PsychtoolboxKernelDriver.m.

-> 64-Bit kernel driver of OSX with 64-Bit kernels rebuilt. Screen for
64-Bit Octave/Matlab on OSX rebuilt. We don't care much about the
deprecated 32-Bit PTB and 32-Bit kernel for OSX anymore -- no update.
-> Screen for Linux 32/64-Bit Matlab/Octave rebuilt.
-> Tests pending.
SetCompressedStereoSideBySideParameters(): Adapt to use with panelfitter.

-> Use raw width/height of window, not scaled size.
-> Makes ImagingStereoDemo(102) work with panelfitter on.
PsychDataPixx: Fix 'En/Disable''BlueLine/ScanningBacklight' on old Datapixx files.

Was still the wrong way to skip setup of unsupported functions.
Now should work. Tested on 64-Bit Octave on Linux, for which we
don't have updated Datapixx mex files yet.
Merge pull request #94 from kleinerm/master

Pull: Add support for NV-E0 GeForce-600 series "Kepler" gpu's.
Merge pull request #95 from Psychtoolbox-3/master

Post-Release fix for BETA: OSX support for NVidia GeForce 600 Kepler gpu's.

* On OSX by updating the PsychtoolboxKernelDriver for 64-Bit kernels.
* Also enable experimental support for 4 display heads on Kepler gpus.
* Small fixes to PsychDataPixx and panel scaler support for side-by-side stereo.