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

If this method is simply enumerating the number of addresses defined for a given interface, why do we need to scan for a user specified label? Given output like so:

```lo1: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
>.......options=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6>
>.......inet 10.0.2.21 netmask 0xffffffff.
>.......inet 10.0.2.22 netmask 0xffffffff.
>.......inet 10.0.2.23 netmask 0xffffffff.
>.......inet 10.0.2.24 netmask 0xffffffff.
>.......inet 10.0.2.25 netmask 0xffffffff.
>.......inet 10.0.2.26 netmask 0xffffffff.
>.......inet 10.0.2.27 netmask 0xffffffff.
>.......inet 10.0.2.28 netmask 0xffffffff.
>.......inet 10.0.2.29 netmask 0xffffffff.
>.......inet 10.0.2.30 netmask 0xffffffff
```
Can't we just count the number of times `inet` is specified?