Display facts for aliases in *BSD

* interfaces.rb - aliases on *BSD are iterated over up to their actual count - slightly modified Michelle Sullivan's version
* util/ip.rb - added get_alias_no method to return alias count; method get_interface_value modified by Michelle Sullivan to allow obtaining values for specific aliases

Originated here:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=190796

This is correct, however just for reference - the order of adding ( set in /etc/rc.conf by the numeric suffix of the alias definition ) will result in the alias order (alias 0..n ) ..  Whilst specifying _alias0 _alias3 in /etc/rc.conf will work, it's highly frowned on as many scripts reading the config will not process correctly (particularly if they are trying to match to 'live' aliases)