Update modules: apache, squid, useradmin.

From the webmin updates page:

• Apache Webserver: if Webmin is used in non-english language mode, "<Directory>" sections created using this module may be wrongly written out as something like "<Directorio>".

• Squid Proxy Server: the cache_dir directive is not properly supported in squid 2.4.

• Users and Groups: passwords for users created or modified from a batch file are not set correctly.

(see also http://www.webmin.com/webmin/updates.html)

While I'm here, check if a webmin configuration directory already exists at
install time (post-install target): in this case, automatically run the webmin
setup script (it will insert the proper Perl paths in the webmin scripts).

Users who have multiple or different configuration directories will have to
run the script manually, as before.

PORTREVISION bump to advertise the new changes.