* WIP extrinsic api updates
* First pass done; now to get things compiling again
* document and tweak new structs/traits
* cargo check --all-targets now compiles without issue
* Polkadot and Substrate take different extra params; support both
* Fix transaction format (missing byte from AccountId -> Address) and fmt
* Tweak Signer trait
* Tweak comments and such in extrinsic params
* check all examples against newer polkadot, add new one with params, import path tweaks
* clippy fix, and save an allocation when signing
* Remove unnecessary Default clauses
* Tidy up and fix comments. Panic if payload size >4GB
* fix typo
James Wilson