Remove unused methods, use snake_case
Add some more caching

* Cache room attribute values in Redis
* Memoize various functions during a single request context
Provide 5 instead of 3 stack frames in db log
Avoid warning about empty IN clause
Remove debug print
Improve import order in alembic script template
Fix wrongful rename
Use schemas for tables

* Core: indico
* Roombooking: roombooking
Properly handle schemas everywhere

- when deleting all tables
- when prepareing a new database
- when creating tables