core (memory/sqlite): renamed column for files from hash to file_hash: the version has not been changed to avoid too creating update for such a small change. Even if generally a database change means a version change, this one has not be wide spreaded, and it will be updated automatically for dev version. A manual "drop table files" using sqlite3 shell might clean things up though. The reason of the column name change is that hash is named file_hash in code (because "hash" is a reserved word), and using the same name simplify data manipulation.