- Arguments are now parsed. mod_tmcd handles 'version', 'redirect', and
  'vnodeid' directly.  Arguments to the called function are encapsulated in the
  'args' argument.
- The command to execute is now part of the filename, not an argument.
- Errors are mapped to HTTP protocol status codes (unknown command returns 404,
  redirect from a host other than boss returns 403, errors from inside libtmcd
  return 500, etc).  The status line returned with these errors provides more
  information about why the request failed ("403 Requires Encryption" if SSL is
  required, "400 Invalid Version" if the version argument isn't an integer,
  etc).  This way the client can tell why the request failed.
- More libtmcd cleanup.