2.21 [KK 2008-10-14]
- Fixed round-robin dispatching with only 1 configured back end. The
  bug was that on the next-time around, no "other" back end would be
  found.
- Centralized reading/writing from fd's and buffer handling into class
  Netbuffer. This removes superfluous buffer copying in the HTTP
  dispatcher.
- Rewrote HTTP dispatcher & (hopefully) optimized it.  
- Added Profiler class and xr/etc/xrprof tool.  
- Many other small changes.
- Added docs on maxconn flags and weighted-load dispatching.
- THIS VERSION IS A REWRITE OF THE HTTP DISPATCHER. IT IS ALPHA-QUALITY.