Ranking for function signatures.

Here's a starting point for how we *might* objectively rank function signatures.

- Let `C` be the set of all contract addresses which contain bytecode matching the pattern used to `JUMPDEST` based on the first 4 bytes of the message data.

With just `C` we can establish a basic ranking for signatures. This ranking is however trivial to game.

- Let `T` be the set of all transactions who's first 4 bytes match the signature.

With `len(T)` or `sum(t.gas_price * t.gas for t in T)` we should have a less easy to game metric. I suspect that this will be suitable until we find someone directly attacking the rankings at which point we can iterate on this.

Question is, how do we easily get these metrics. I think there is a BigQuery database for most of the chain data that I may be able to get access to, otherwise, maybe someone else knows of a relational database with all the chain data?