What's src/bitset.cc for?

[Benjamin Kosnik]

> in src there is a file "bitset.cc" which looks like it was an
> implementation of bitset, but is actually unused, and also the bit
> counting function looks very bogus. Is this work in progress or
> abandoned?

abandoned. There's no status via the ChangeLog, so I'll just remove it. 
It hasn't actually been part of the compiled library for at least a year.

-benjamin