Bump version number to 3.0.12, add detection code for supported OS releases.

Bump module version number and Psychtoolbox version and date.
A new function PsychSupported() returns a string which describes the
status of official support for given operating system release.
Screen(‘computer’) returns this as new subfield ‘supported’, as does
the startup info of Screen(). Linux is fully supported. OSX 10.9 is
fully supported. Windows-7 is fully supported, Windows 8.x is partially
supported, Windows Vista and XP are unsupported.

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