Added some more MD5 support to Apache:

* A new module, mod_digest, which supports digest authentication, as per
  draft-ietf-http-digest-aa-02. Could use some work in terms of being a bit
  more secure in terms of nonce-generating and so forth, and it needs a
  support/ utility to generate htdigest file entries. Use it the same way
  as in NCSA httpd 1.5; AuthType Digest, and use AuthDigestFile to point
  at the file.

* A new server or per-directory directive, ContentDigest. Set it to On,
  and Apache will generate a Content-MD5 header with each file sent. This
  may or may not be useful, and there has been some discussion on http-wg
  about removing this from the spec (it is currently vaugely defined in
  the 1.1 draft), but it doesn't hurt anything.

Reviewed by: Everyone. At least, no one objected during the two weeks given.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@76403 13f79535-47bb-0310-9956-ffa450edef68