Updated package to newest version, 4.0.4. Changes include:
* GnuTLS: compatibility with GnuTLS-3.4.2
* Nethttpd_plex: the post_add_hook was not called by accident
  (since OCamlnet-4); this is now fixed.
* Nethtml: new option case_sensitive
* GnuTLS: initializing the library on-demand. This avoids that
  /dev/random is kept open all the time since program start, and
  works around incompatibilities with Netplex. (Thomas Calderon
  found the problem.)
* GnuTLS: setting DH parameters on certificates (this was forgotten in
  previous releases). (Thomas Calderon found the problem.)
* GnuTLS: supporting GnuTLS versions where SRP is disabled.
  Supporting GnuTLS-3.4.
* OpenBSD build: fix linker option (Christopher Zimmermann)
* Equeue: There is a new method request_proxy_notification,
  which is only used by Uq_engines.qseq_engine (but unfortunately
  needs to appear in the public type of the object). This new
  method permits that chains of Uq_engines.qseq_engine pairs
  can now be arbitrarily long without consuming too much memory
  and without the danger of getting stack overflows.

  This fixes issues where notification chains got too long. In
  particular, we saw a stack overflow when retrieving a video
  stream via HTTP. The stream was sent with many chunks, resulting
  in a long Uq_engines.qseq_engine chain.

  Implementers of engines can simply define request_proxy_notification
  as no-ops.
* Nethttp.set_content_range: this function generated an incorrect
  header (the "bytes" word was missing). (T旦r旦k Edwin)
* _oasis is generated from _oasis.in
* Netplex: the Netplex socket directory has a different default
  if not specified in the config file.
* Netshm: the POSIX specifier has now two args
* IPv6: automatically enabled if there is a global IPv6 address
  * Unicode tables: Moved them to a separate netunidata library.
  This library needs to be linked in for getting access to the
  tables (this is no longer the default).
* Renamings: Http_client, Ftp_client etc. => Nethttp_client,
  Netftp_client
    Mimestring => Netmime_string
  Xdr => Netxdr
* Netmime: moved functions to Netmime_header and Netmime_channels
  * Netmech_scram: Removed the check that passwords only consist of
  ASCII chars. The user can now call Netsaslprep.saslprep.
  * Removed: rpc-auth-dh, nethttpd-for-netcgi2
* Http_client: the authentication mechanisms are now encapsulated
  in a first-class module HTTP_MECHANISM. So far, there is Digest
  authentication in this form. The signature of HTTP_MECHANISM
  is similar to SASL_MECHANISM.

  Another visible change is that the insecure Basic authentication
  is no longer enabled for non-TLS-secured connections. This can be
  changed back by setting flags, though.

  Some fixes in the design improve Digest authentication for proxy
  connections.
* Netpop: implementating SASL authentication for POP3. Moved Netpop
  into netclient.
* Netsmtp: implementing SASL authentication for SMTP. Moved Netsmtp
  into netclient.
* Adding a framework for SASL, and a number of mechanisms
  (PLAIN, CRAM-MD5, DIGEST-MD5, SCRAM-SHA1).
* fcgi/scgi/ajp connectors: exporting a handle_connection function,
  and unifying existing such functions (Christopher Zimmermann)
  * adding support for modular cryptography (symmetric ciphers and
  digests)
* SCRAM is now implemented with the new crypto providers
* removing dependency on Cryptokit
* removed library netgssapi; now part of netsys/netstring
* removed library netmech-scram; now part of netstring
Ocamlnet-4 adds:
- new library netgss-system
- new library nettls-gnutls
- removed equeue-ssl and rpc-ssl
- X.500 modules Netasn1, Netdn, Netx509
- Crypto definitions Netsys_crypto_types, Netsys_crypto
- TLS modules Netsys_tls, Nettls_support
- Support for SASL and GSSAPI
- Moved many functions from Uq_engines to new modules in
  the equeue library (Uq_client, Uq_server, Uq_multiplex,
  Uq_transfer)

(jaapb)