* add follow_stream impl
* follow_stream_unpin first draft
* add tests for follow_stream_unpin
* more tests and fixes for follow_stream_unpin
* first pass follow_stream_driver
* follow_stream_driver: add tests, fix things, buffer events from last finalized
* First pass finishing Backend impl
* Fix test compile issues
* clippy fixes
* clippy fix and consistify light_client
* revert lightclient tweak
* revert other lightclient thing
* cargo fmt
* start testing unstable backend behind feature flag
* more test fixes and move test-runtime metadata path just incase
* fix compile error
* ensure transaction progress stream actually used and fix another test
* cargo fmt
* CI tweak
* improve some comments and address some feedback bits
* update CI to use our own nightly binary
* wait for finalized block perhaps
* Add and use subxt-signer crate for WASM compatible signing
* cargo fmt
* dev keypairs already references
* WIP fix various breakages
* re-jig features to be simpler and various test fixes etc
* doc and web fix
* fix various bits and pieces
* fix a test I broke
* dev-deps can't be linked to in docs, hrmph
* cargo fmt
* another doc link
* document the subxt_signer crate more thoroughly
* move feature flag for consistency
* more docs, no default subxt feature flag on signer, update release instrs
* Add missing license header
* unwrap_inner => into_inner
* extend a test a little to better check derive junctions
* note more clearly that the crypto bits come from sp_core::crypto
James Wilson