Screen/OSX: Fix typo which caused compile failure.
osxmakeit: Cosmetic.
Bump minimum required OSX version for mex files to 10.8 Mountain Lion.

We now require at least OSX 10.8 Mountain Lion and fail on any earlier
OSX version, as various workarounds for 10.7 and earlier were removed.

-> mexopts.sh for Matlab and osxmakeitoctave3.m for Octave updated.
Fix build of moglcore/moalcore et al. on OSX.

Including uchar.h doesn’t work on OSX, only on Linux, so make that
#include
conditional on Linux. On OSX we don’t need hacks for Octave. For OSX
and Matlab, we use a “-Dchar16_t=UINT16_T” in mexopts.sh to define the
missing data type manually.
All mex files for 64-Bit OSX (Octave 3.8 and Matlab R2012a) rebuilt.

Except for Datapixx mex which will need special treatment.