CVS log for: TODO

Keep-alive actually works now.  Major request parsing cleanup.

- pth_writev() is used to combine headers with body instead of issuing
  multiple pth_write()'s; this should be faster because it results in
  fewer internal copies of the data
- filename(s) of index files can be set in cow.conf now
- added ability to limit response concurrency

Popular mime types now bubble up to the top of the list, making mime lookup
less expensive as time goes on.

- fixed critical bug that caused only the first part (probably about 256K)
  of a file to actually be returned to the user
- CoW was using a pool of pmsg structures for communication between the
  main thread and the depot, but was malloc'ing messages sent from the
  depot to the handlers; messages are now forwarded to handlers instead of
  copied so we avoid the malloc overhead
- CoW now re-uses server socket so we don't have to wait a couple minutes
  after shutdown before restarting (avoids "Address in use" messages)

 * Added mime options to config file
 * Removed some unused constants
 * A little bit of error logging
 * Better detection of OS file descriptor limits

Many changes:
 - beginning of logging support
 - fix bug in Makefile for config.l.c
 - code reformatting
 - prepare for release (AUTHORS, Changelog, etc.)