Currently, if SQLite cannot find a table or index referred to by a query, it reloads...

Currently, if SQLite cannot find a table or index referred to by a query, it reloads the database schema from disk to see if the table or index has been added since the schema was cached in memory. Extend this behaviour to columns (which may have been added using ALTER TABLE) and fix some obscure cases related to tables and indexes (INDEXED BY, DROP TABLE etc.).

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