* finalization for in_mem
* fetch last finalized block
* pruning: use canonical term instead of final
* finalize blocks in full node
* begin to port light client DB
* add tree-route
* keep number index consistent in full nodes
* fix tests
* disable cache and finish porting light client
* add AsMut to system module
* final leaf is always best
* fix all tests
* Fix comment and trace
* removed unused Into call
* add comment on behavior of `finalize_block`