Removed FEATURE_DENY_GZIP and replaced it with client_accept_encoding,

   client_te and client_accept_encoding_adder, triggered by the new
   +no-compression action. For HTTP/1.1 the Accept-Encoding header is
   changed to allow only identity and chunked, and the TE header is
   crunched. For HTTP/1.0, Accept-Encoding is crunched.

parse_http_request no longer does anything than parsing. The rewriting
  of http->cmd and version mangling are gone. It now also recognizes
  the put and delete methods and saves the url in http->url. Removed
  unused variable.

renamed content_type and content_length to have the server_ prefix

server_content_type now only works if csp->content_type != CT_TABOO

added server_transfer_encoding, which
  - Sets CT_TABOO to prohibit filtering if encoding compresses
  - Raises the CSP_FLAG_CHUNKED flag if Encoding is "chunked"
  - Change from "chunked" to "identity" if body was chunked
    but has been de-chunked for filtering.

added server_content_md5 which crunches any Content-MD5 headers
  if the body was modified.

made server_http11 conditional on +downgrade action

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