cleaned up zombie, skeleton, enderman

there are still problems with the way things are being drawn with
enderman.
does not appear to be a problem with the OBJ.
similar issues with texture transparency and face clipping in grass and
and human model currently.

Signed-Off-By: Hung-Lin <nymphalis.aloft@gmail.com>
Merge pull request #499 from Meiun/Meiun2

cleaned up zombie, skeleton, enderman