better names for some arc server internals
idiom: use either while conditions or break/continue
srv.arc cleanup

1. unit tests
2. separate low-level header parsing from http dispatch.
3. better function names
4. staged lifetimes of temporaries; circumscribed string operations
.
bugfix: handle browsers that don't send cookies
easier to read with headers inlined
support for basic auth

http://en.wikipedia.org/wiki/Basic_access_authentication