add basic interface alias support. for now (since we don't use ip in our network...

add basic interface alias support. for now (since we don't use ip in our network scripts yet), it adds :1, :2, ... alias interfaces this will change when we add support for the ip utility, but the config format will remain the same. example:

config alias     test
option interface lan
option ipaddr    192.168.1.1
option netmask   255.255.0.0

SVN-Revision: 12241