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

Using a regex like `/inet/` would match both inet and inet6. My concern is that this method looks like it largely duplicates the functionality of `.get_interface_value`, and if there's a lot of overlap I would like to know if there's extra code that we can trim from the function.