Log Message:
Update to 2.21.  Significant changes:

- 2.21 | 2007-10-04
  - license now GPLv3+ (see COPYING)

- 2.20 | 2007-05-16
  - (www cgi) proc deleted: cgi:make-cookie (notice given in version 2.14)
  - distribution includes docs in HTML

- 2.19 | 2007-05-14

- 2.18 | 2007-02-16
  - new `(www server-utils answer) mouthpiece' command: #:add-direct-writer
  - new module: (www utcsec)

- 2.17 | 2007-02-01
  - new proc in (www server-utils big-dishing-loop): echo-upath
  - changes to make-big-dishing-loop
    - bugfix: #:socket-setup works (crippling typo corrected)
    - for #:concurrency #f, no longer close port when done
    - for #:concurrency non-#f, "parent" calls #:parent-finish proc
    - unless #:need-input-port, "child" does `shutdown 2' on the socket

- 2.16 | 2006-07-14
  - make-big-dishing-loop accepts keyword arg #:concurrency

- 2.15 | 2006-04-26

- 2.14 | 2006-02-19
  - (www cgi) now handles unset HTTP_ACCEPT
  - additions to module (www server-utils answer)
    - string: CRLF
    - procedure: fs
    - procedure: walk-tree
    - procedure: string<-header-components
    - `mouthpiece' #:add-header now also takes boolean NAME
  - new module: (www server-utils cookies)