Enhancement: Allow parsing of abbreviated IPv4 CIDR addresses

[darrinsmart]

This works:
let net4 = Ipv4Net::from_str("10.1.1.0/24").unwrap();

But this doesn't:
let net4 = Ipv4Net::from_str("10.1.1/24").unwrap();

This abbreviated form of IPv4 CIDR - omitting trailing 0 octets, is fairly common, it would be great if ipnet could accept these.

[krisprice]

HI @darrinsmart -- I'll keep this issue around to track and when I have time implement this. Thanks 👍

[benmaddison]

@krisprice although I can appreciate that this might be useful in some applications, it will break others if it's done silently in the FromStr impls. There are plenty of places (e.g. most vendor config syntaxes, RPSL) were the abbreviated form is not legal.
I'd suggest a separate constructor for this.