serde support

[mkpankov]

Hi. I'm working on a Lua-based test engine and I'd like to make it as general as possible. So I intend to return and serialize an AnyLuaValue to JSON for another process to parse that JSON and make sense of the script result.

What's your stance on implementing serde for AnyLuaValue in-crate here? I tried using serde foreign types support and that seems to work, but I figured this functionality would benefit other people as well.

I can work on that myself but I'd like to make sure PR lands in such case, so that it's not wasted effort.

Would you accept serde implementation under an optional Cargo feature?

[tomaka]

Would you accept serde implementation under an optional Cargo feature?

Yes! Thank you.