ipnet 2.7.1

Provides types and useful methods for working with IPv4 and IPv6 network addresses, commonly called IP prefixes. The new `IpNet`, `Ipv4Net`, and `Ipv6Net` types build on the existing `IpAddr`, `Ipv4Addr`, and `Ipv6Addr` types already provided in Rust's standard library and align to their design to stay consistent. The module also provides useful traits that extend `Ipv4Addr` and `Ipv6Addr` with methods for `Add`, `Sub`, `BitAnd`, and `BitOr` operations. The module only uses stable feature so it is guaranteed to compile using the stable toolchain.