added function to compute line plane intersection
made it to save file cocoa binding outputs error message if save failed
added code to import a simple3d model
added methods to update eye and focus positions on camera and started prototyping an incomplete method for rotating the camera
added method for getting the height of a renderable object

added another constructor for renderable object that doesn't need a texture
changed how projective texture coordinates are computed in shader

changes needed to get planar reflections working again

more work on chess scene