keep custom alias and enable forwarding

hey there, i switched the vacation-plugin of my setup today, after upgrading rc, so i had to dive into this again.

according to the sql-driver: i combined @lluis solution for keeping custom aliases with the need of forwarding. so here is an other set of default sql.
this is still not perfect! since the user, in order to remove a forwarding would have to deactivate that without changing the forwarding adresses. so one should either lock editing the forwarder, while the responder is active or keep track of the previous forwarder and provide it in a variable in order to remove it. also a checkbox to enable, disable forwarding separatly would be great. i didnt have the time today to dive deeper into the rc-pluginstuff, so i leave it as is and hope someone else who knows the rc-stuff is going to do that.

i also did little on the layout.

changes:
config.inc.php.dist
 - SQL: nondestructive adding and removing of autoresponder and forwarder

vacation.php
 - scrollable settingsframe for small windows
 - bigger inputfields

todo:
- [ ] keep track of previous forward OR enable/disable forwarding seperatly