* Hash-deduplicated state storage (and migrations) for PostgreSQL and SQLite
* Refactor droomserver database setup for migrations
* Fix conflict statements
* Update migration names
* Set a boundary for old to new block/snapshot IDs so we don't rewrite them more than once accidentally
* Create sequence if not exists
* Fix boundary queries
* Fix boundary queries
* Use Query
* Break out queries a bit
* More sequence tweaks
* Query parameters are not playing the game
* Injection escaping may not work for CREATE SEQUENCE after all
* Fix snapshot sequence name
* Use boundaried IDs in SQLite too
* Use IFNULL for SQLite
* Use COALESCE in PostgreSQL
* Review comments @Kegsay
