Improve texture loading.
Improve texture loading.

Is a single assimp model uses the same texture repeatedly, we don't need to reload the texture once for each time that it is used.

runewake2/opengl-examples,JohnRThomas/opengl-examples,runewake2/opengl-examples,JohnRThomas/opengl-examples,JohnRThomas/opengl-examples,runewake2/opengl-examples,JohnRThomas/opengl-examples,runewake2/opengl-examples