Fixed bug in glTexSubImage2D

This bug occurred when the first style of glTexSubImage2d is used with 7 arguments.  It looks like it was copied and pasted from the glTexImage2d (6 args) without the argument being changed from 5 to 6.
Merge pull request #396 from wreardan/master

Fixed bug in glTexSubImage2D
Merge branch 'master' of git://github.com/phoboslab/Ejecta