Alex Bocharov

Add optional RKYV serialization support

3

[rkyv](http://github.com/rkyv/rkyv) (archive) is a zero-copy deserialization framework for Rust. This will enable use of `IpLookupTable` data structure in zero-copy fashion, e.g. using memory-mapped file with [mmap-sync](https://github.com/cloudflare/mmap-sync) crate.