add some OpenGL timers

To see what the rendering really costs
mathfun: ignore extra GCC warning

Don't want to edit the source, since it works. Just ignore
warnings as they appear in that file.
make: got rid of strict aliasing warnings

Unfortunately I still don't know a good/performant way to get rid of the
strict aliasing warnings on newer GCC's. Creating a union is not really
desirable as it's been reported to lower performance and creates a lot more
typing work. The cases that are in the codebase now are false positives
though.