Replaced 6 boolean members of csp with one bitmap (csp->flags)

Replaced 6 boolean members of csp with one bitmap (csp->flags)

Moved downgrading of the HTTP version from parse_http_request to
  chat(), since we can't decide if it is necessary before we have
  determined the actions for the URL. The HTTP command is now
  *always* re-built so the repairs need no longer be special-cased.

filter_popups now gets a csp pointer so it can raise the new
  CSP_FLAG_MODIFIED flag.

Bugfix

Added configurable size limit for the IOB. If the IOB grows so
  large that the next read would exceed the limit, the header
  is generated, and the header & unfiltered buffer are flushed
  to the client. Chat then continues in non-buffering,
  non-filtering body mode.