Renamed entire namesace from glext to gl_wrapper

Change-Id: Ic50c38028c06a9ce9868d0ce7fb42508dd1c4257
Reviewed-on: http://www.matthewh.me/gerrit/5
Reviewed-by: Matthew Hoggan <matthew.hoggan@matthewh.me>
Tested-by: Matthew Hoggan <matthew.hoggan@matthewh.me>