Step 1: load your image. One possibility is to use the ppm library from
/usr/class/cs248/support/lib/*/libppm.a to read PPM files. Another
possiblilty is to use the code in
/usr/class/cs248/support/src/glut-3.7/progs/advanced97/texture.{c,h}
to read RGB files.
Step 2: Establish a texture context. There has to be a different context
for each texture that you use. (You can also reload each texture each time
you use it, but that's really slow.)
