* make service use both finalized and non-finalized state
* Document new functions
* add documentation to sled fns
* cleanup tip fn now that errors are gone
* rename height unwrap fn
This commit begins the process of integrating `zcash_script` with the rest of the system for verifying scripts while syncing the block chain. It does so by adding the necessary support for looking up UTXOs from the state service and implements the first parts of the `script::Verifier` for looking up the necessary UTXOs in the state and then generating the necessary call to `zcash_script` to verify the script itself.
Co-authored-by: teor <teor@riseup.net>