Split ABIv2 encoding/decoding

[slawomir-pryczek]

Maybe it'll be good to spli this project into separated project just for ABI encoding/decoding which other php projects for interacting with ethereum based nodes can use. I think nothing else supports abiv2/tuples as good as this one and this is rather complex to implement and test properly so it should benefit everyone else writing php code, if they'll just use this one.

[drlecks]

Not a bad idea. I'll think about it. 👍