Initial SWIG support for the bfbin library
Fixed two bad-pointer problems
Replaced condition variables and mutexes with barriers

pthread_cond_signal() doesn't guarantee that the signal is delivered.
Specifically, if no threads are waiting on the condition variable,
pthread_cond_signal() does nothing.  This revision replaces the
handshake protocol with one based on pthread_barrier_wait(), which
seems to work so far.
Began writing a Python demonstration of the SWIG interface
Rewrote the thread IPC to use Unix pipes

This is a much simpler approach than the previous attempt at using
barriers, and it actually seems to work so far.
Completed the example of invoking bfbin from Python