Added a TextureCallback which cycles through various filter modes, used in testing new glTextParamters update functionality.  I have commented out the call to attaching of the callback so osgtexture outwardly behaves as before.  The code lies dormant just incase we need to use it for testing in the future.
Added a TextureCallback which cycles through various filter modes, used
in testing new glTextParamters update functionality.  I have commented out
the call to attaching of the callback so osgtexture outwardly behaves as
before.  The code lies dormant just incase we need to use it for testing
in the future.


git-svn-id: 23b6355f2bb369032457de4eb5f713ee134f73a8@450 16af8721-9629-0410-8352-f15c8da7e697

joevandyk/osg,joevandyk/osg,joevandyk/osg,joevandyk/osg,joevandyk/osg