Breaking change (TypeScript with derives only) The return type names for api.derive.* have been adjusted for consistency, all starting with Derive* (previously a mixture of Derived* and Derive*)
Breaking change (derives only) Additional cleanups of democracy proposal & referenda derives, including support for new Polkadot/Substrate vote retrievals

Changes:

Tx signing via signAndSend & signAsync now tries to use the last finalized block (depending on finalized drift)
Add support for api.rpc.childstate.* Substrate RPCs, older nodes with still populate api.rpc.state.* with the child methods
Adjust Error.message on RPC failures to not include the (already known) method signature
Split @polkadot/types/known into @polkadot/types-known, allowing for base API overrides
Extended api.derive.democracy to cater for dispatchQueue and externals
Extended api.derive.council to cater for new phragmen elections
Use new queryStorageAt for query .entries, removing unneeded subscriptions (use as available)
Fix BTreeSet initialization when it forms part of query interfaces
Fix encoding for Vec<u8>-related types as part of constants
Internal adjustment of interface type locations (no impact on imports via @polkadot/types/interfaces)