Screen/OSX: Remove kernel driver compat wrappers.

Replace the old 32-Bit kernel compatibility wrappers by direct calls to
the new 64-Bit interfaces. Makes the code more simple to read and
maintain.
Remove unneeded leftover CGDisplayBeamposition() prototype.
Screen/OSX: Make ConserveVRAM setting 16384 less weird.

The only difference between regular and 16384 is that 16384 avoids
capturing the screen. Unfortunately this doesn’t make a difference in
performance at all.
There’s just no winning with this buggy piece of crap that Apple calls
an operating system.
All mex files for OSX rebuilt.

For PTB beta 3.0.12 SP2.

-> Only OS X 10.10 Yosemite is supported/tested from now on.