[ANN] Update to bit and rex libs: release 16

[Reuben Thomas <rrt@...>]

I've updated my bit and rex libs with fixes (mostly from Thatcher Ulrich)
to make the code compile more cleanly, and in particular, to make bit
compile on Mac OS X, which seems to have a broken ## operator in the C
preprocessor.

I've also added long overdue acknowledgements to Thatcher and to John
Passaniti (from whose own bitwise operations library I stole some cunning
C preprocessor tricks).

Come and get it at:

http://www.mupsych.org/~rrt/Lua