Allow the image_file_name to be NULL. Remove the check for the EXT_texture_object OpenGL extension as we are using the GL core functions now instead and the symbol isn't necessarily defined.
Allow the image_file_name to be NULL.
Remove the check for the EXT_texture_object OpenGL extension as we are using the
GL core functions now instead and the symbol isn't necessarily defined.


git-svn-id: 4705079bc6b8aadf675e3696f5c015a6aa4916e3@1914 3c1deb5b-d424-0410-962d-aba41a686d42

hsorby/zinc,OpenCMISS/zinc,hsorby/zinc,hsorby/zinc,hsorby/zinc,OpenCMISS/zinc,OpenCMISS/zinc,OpenCMISS/zinc