figure out what to do about the ETag headers apache is sending down.

fix up the strcmps for "entry" and "modified", they're a little off, should
also compare namespaces, just in case...

might be nice to switch to a parser that would let us write data out to the
wire as we parse it, instead of having to wait until after we've parsed the
entire file and removed the unneeded entries before we can send any data to
the client.

other rfc3229 IM values:
  - diffe - not sure how hard this will be, or if i care enough to do it.
  - gzip - can i leverage mod_deflate?
  - range - this is simple, definately want to do this first.

have a way to limit this filter to files in a particular directory.

think about support for other formats, like rss.

apr-util's xml stuff seems to do something funky with xml:lang, figure out
what the deal is.

write a makefile/configure script of some sort...