Reworked schema for the snapshots collections and operations with index of master collections. This allowed for better performance while also reducing the index size to a fraction of the previously used ones.

This introduces a breaking change to the database. To migrate, see the added migrate_snapshots.py and add_min_t2s.py scripts. (or delete the current snapshots collection and wait for the t2s to accumulate)

HistoryManager has a new periodic procedure that has to be configured. To migrate, add the following to the configuration:

mark_datapoints_schedule:
  hour: "7,19"
  minute: "45"