OSX Support

Support DIOD on OSX.  Also clean out some of the autogenerated stuff.

This is not a *complete* port, see OSX-TODO for what doesn't work.

In particular: user mapping, anything depending on setfsuid() and friends.

What does work:
diodcat, diodls, diodload, dioddate, diodtop, mounting diod from linux, basic file operations.
misc/ tests

user/ tests need fixing.