clarify that textureDirname parameter is sometimes unused in some of the model loading functions
clarify that textureDirname parameter is sometimes unused in some of the model loading functions

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