Trouble generating an Ipv4 Address from an Ipv4 CIDR

[rvbcldud]

I am trying to use your Rust crate to generate a Ipv4 address given an Ipv4 CIDR like so:

fn main() -> ipgen::Result<()> {
 let network = "10.0.0.0/8".parse()?;
 let addr = ip("test", network)?;

 Ok(())
}

However, I get the following error:

Error: InvalidIpNetwork("[BUG] failed to parse the generated IP address `a83:6304` as IPv4")

Looking at the source code, I don't see anything guarantees that the generated Ipv6 address can be converted back to an Ipv4 address.

Let me know how you can help, @rushmorem!

[rvbcldud]

Furthermore, when running the tests in the library ... it fails on converting from Ipv4.

[rvbcldud]

After messing around with things, it seems that rather than making a Ipv4-compatible address (which is now deprecated in favor of Ipv4-mapped address.

I will make the changes and submit a PR.

[rvbcldud]

Changes made in #3