Ignoring .DS_Store

Signed-off-by: David Brainard <brainard@psych.upenn.edu>
Mac mex files compiled for libsvn.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>
More ignoring of .DS_Store, locally

Signed-off-by: David Brainard <brainard@psych.upenn.edu>