- get domain name by splitting address parameter instead of relying
on the domain GET/POST parameter.
This makes linking to edit-alias easier.
- simplify reading $_GET/$_POST['address']
git-svn-id: https://svn.code.sf.net/p/postfixadmin/code/trunk@749 a1433add-5e2c-0410-b055-b7f2511e0802