rzscore kinda compiles, no testing done yet.

Some other library stuff is here, too. No SDL yet, want to
get enumeration and claiming done first.
test what we have written (seems to work!)
Added interface claiming, sort of. Not tested.

I'm going to have to figure out how to do
libusb transfers. My most likely strategy
will mimic libusb's -- one set of functions
for synchronous transfers and one for
async. As can be expected, asynchronous may
require some more care and feeding (or at
the very least, require the end programmer
to prod the libusb event loop -- or maybe
I can provide a rzswitchblade function to
basically do that and perform callbacks
via rzswitchblade rather than libusb).

I will probably wind up finishing synchronous
transfers first.