this also fixes a problem with ignored vhost subdomains on validation

- Make sure ISPConfig shows the correct error message (instad of an SQL error) when a website is renamed after an alias domain that still exists.
- It should be possible to create two websites with the same domain on the same server as long as the IP differs. I therefore changed the serverdomain index of the web_domain table to include the IP address.

Fixed/Implemented: replaced intval() by $app->functions->intval() in all interface functions due to big number problem in intval()

If you change an auto subdomain of an alias/web-domain there has to be checked if a subdomain with www. or *. has been created already.

Implemented: FS#2427 - Allow wildcard subdomain creation on limit_wildcard = y