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

`tmp1` is always going to be defined as an array with zero or more elements, so we don't need to see if `tmp1` is defined and then use the length if it is - we can always call `tmp1.length`.