Problems with timestamps in the database

All tables should be provided with a created_at and updated_at timestamp.

The timestamp column that exists in some tables is ambiguous and could stand for a created_at, updated_at or deleted_at. This column should be adapted to the convention and should be renamed to one of created_at, updated_at or deleted_at.

The last_login timestamp in the account table does not update when logging in. Furthermore, the possibility of adding a last_active column in addition to the last_login column should be examined.