Witness update

Witness

@pishio
Updated witness nodes to 1.27.3

Blockchain features changes (nonconsensus changes, so no hardfork needed):
Minimum rc_delegation feature: !775
Improved RC delegation processing: !793
Improved RC cost calculation for recurrent_transfer operation, to better express blockchain resource usage: !803

API changes/fixes:
Fixed filtering in the database_api::list_proposal_votes, MR: !773
Fixed argument initialization for list_rc_accounts, list_rc_direct_delegation APIs to avoid random hived node behavior in case they are not explicitly passed by caller. #422
General bugfixes:
Fixed broken decimal conversion of fc::uint128 type: #426
Improved verification of chain-state (stored in shared_memory.bin file) to detect cases when new index has been added to already filled state file (what should be disallowed, can can lead to further problems and damaging data structures). Issue #423
cli_wallet changes:
simplified method definitions to improve gethelp output readability: #425
General changes:
Default seednodes list has been updated.