* Bump nim-stew
why:
Need fixed interval set
* Keep track of accumulated account ranges over all state roots
* Added comments and explanations to unit tests
* typo
* Provided common scheduler API, applied to `full` sync
* Use hexary trie as storage for proofs_db records
also:
+ Store metadata with account for keeping track of account state
+ add iterator over accounts
* Common scheduler API applied to `snap` sync
* Prepare for accounts bulk import
details:
+ Added some ad-hoc checks for proving accounts data received from the
snap/1 (will be replaced by proper database version when ready)
+ Added code that dumps some of the received snap/1 data into a file
(turned of by default, see `worker_desc.nim`)