Add very quick and dirty GLUT port

Add a very quick and dirty GLUT port. Works on OS X 10.9
Add very simple test mode that outputs screenshots for later comparison

Add a very simple test mode which outputs PNG screenshots of each frame to the current directory. This is useful to make sure that ep.c code changes/cleanup are not affecting the output.

Note that these screenshots are very dependent on GPU/driver/OS--in my experience they aren't even the same between 2 GPUs (integrated/discrete) on the same laptop!
Make sure to generate the reference/test PNGs with the same configuration.

- Compile using 'make test'
- electroportis_glut will run for 10000 frames and dump screenshots in the current directory
- Make changes and compile/run again (in a different directory)
- 'diff -r' the two directories to determine if the output changed
ep.c: Remove unused virtual sp register
ep.c: exprand(): Clean up dead stores and saving/restoring registers
ep.c: twixt(): Clean up
ep.c: setacttargets(): Clean up
ep.c: display(): Clean up
ep.c: value(): Clean up
ep.c: animateacts(), stopAnimation(), foldtwixt(): Clean up
ep.c: processCommand(): Clean up
ep.c: createActTable(): Clean up
ep.c: createBlankActAnim(): Clean up
ep.c: killSeq(): Clean up
ep.c: tasteQueue(): Clean up
ep.c: drawshape(): Clean up
ep.c: drawit(): Clean up
ep.c: hls_to_rgb(): Clean up
ep.c: readAnimation(): Clean up
ep.c: Simplify createActTable() and createBlankActAnim()
ep.c: Simplify drawshape()