Framework for improved RPC unit tests

Should more or less work now.

* use #[repr(C)] for all hash types

* use a zeroed buffer in crypto::ec::sign

* eliminate most usages of unsafe in crypto::ecdh::agree

* eliminate all possible unsafety in crypto module

* Basic signing queue

* Adding docs

* WebSockets server for signer

* Removing TODO

* Shortening the syntax

* Exposing types from RPC

* Fixing indentation

* Update main.rs

Fixing few clippy warnings

Change eth_signAndSendTransaction to personal_SignAndSendTransaction

also adds an EthTester struct for more test flexibility.

this has the added benefit of allowing the removal of redundant upgrades.

Support "earliest" and specific block parameters in RPC where possible