Fixed loading of .3ddv files created on Mac OS X.
Fixed loading of .3ddv files created on Mac OS X.

.3ddv files are really just ZIP files. On OS X, ZIP files are created
with a containing directory for all the files (so that unzipped it
doesn't scatter loose files all over your desktop). However, 3DDV wasn't
properly created this containing directory when unzipping the file. Now
it does.

mdippery/3ddv,mdippery/3ddv