Incompatible with Tendermint 0.16

[d10r]

Due to tendermint/abci#205, this implementation has become incompatible with Tendermint v0.16 and newer.

The breakage was caused by how varints are now encoded.
Instead of a custom encoding, Tendermint now uses the protobuf default approach of ZigZag encoding.
rust-protobuf seems to support that encoding (see doc).

The update likely also requires syncing src/types.proto to the one in tendermint/abci (as far as I understand, it needs to be v1.10+). I already tried that (manually with protoc on the cmdline), but didn't yet manage to compile the included https://github.com/tendermint/abci/blob/master/types/types.proto such that the types KVPair and KI64Pairget properly included and namespaced.

Btw. the README lacks the information that protobuf support needs to be installed on the system.

[ebuchman]

Maybe @zmanian or @adrianbrink can help here

[froggrog]

@d10r i'm fix it abci-rs

[zmanian]

Can we sync on https://github.com/tendermint/amino_rs

[froggrog]

@zmanian i think it's a good idea. how do we implement it?

[zramsay]

closing for #12, @JacksonCoder has a fork that is using latest tendermint