Remove all information not strictly used by the frontend as well as
any index information. This will make it easier to create a SQLite
database from the schema.
VALUEs() is not a cachable construct in SQLAlchemy, so use arrays
instead. Also add a special case for single results, the usual result
for reverse queries.
Also defines an extended connection object that includes access to
the table definitions. Makes it easier to access the tables from
code that has been split off into separate modules.
