Update courier ports to latest releases

[madpilot]

Summary

I'd like to update the devel/courier-unicode port to the latest version.

It contains a library major version bump, so I also updated all the dependent ports, since new version have been made available at the same time.

Can you test and approve this patch for your port?

The updated imap server works fine for me.

[madpilot]

I forgot to note that sqwebmail has grown an hard requirement for gnupg. I found no way to avoid that.

[oliver]

For me and my affected ports, the Diff looks fine. Like we discussed via mail Guido, you are free to continue maintaining my courier ports by taking the maintainership because I moved long time ago away from courier to dovecot.
Ports are:

databases/courier-authlib-mysql
databases/courier-authlib-pgsql
databases/courier-authlib-userdb
databases/courier-authlib-usergdbm
mail/courier-authlib-vchkpw
net/courier-authlib-ldap
security/courier-authlib
security/courier-authlib-base

mail/courier-imap

Thank you!