* Started implementation of state endpoints.
* Add rpc calls and server stubs.
* Initial implementation of getAccountProof and getStorageProof.
* Refactor validation to use toAccount utils functions.
* Add state endpoints tests.
* Add toContentKey helper functions.
* Implement typed lookup functions for getting account and storage trie nodes and bytecode.
* Re-implementation of recursive gossip.
* Offer validation improvements. Don't allow key end in Nibbles for leafs as defined in the spec.
* Minor refactor to validation and add addition bytecode check.