CVS log for: pmsg.h

Lots of changes:
 * Use either buffering code taken from Apache or TCP_CORK to minimize
   network traffic.
 * Sockets are now properly 'half-closed' before being truly closed
 * Make 503 responses a compile time option
 * Make HTTP PUT a compile time option
 * Added -b command line switch to change server's accept backlog
 * Lots of code cleanup
 * More statistics kept for verbose (-v) output

- 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)

Force accept thread to wait if the depot falls behind and has a full message
queue.  This prevents the accept thread from reusing pmsg structures before
the depot has processed them (premature reuse of these structures caused the
same message to be placed on the message queue multiple times which caused
all kinds of internal pth problems).

Also fixed a couple compile-time warnings.

Initial import of Takashi's CoW code (version 0.3.2).

Initial revision