* Miscellaneous updates TBC
* Disentangled pivot2 module from snap
why:
Wrote as template on top of sync so it can be shared by fast and snap
sync.
* Renamed and relocated pivot sources
* Integrated `best_pivot` module into full and snap sync
why:
Full sync used an older version of `best_pivot`
* isolating download module from full sync
why;
might be shared with snap sync at a later stage
* 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`)
Jordan Hrycaj