levels.go
func closeAllTables(tables [][]*table.Table) {
	for _, tableSlice := range tables {
		for _, table := range tableSlice {
			_ = table.Close()
		}
	}
}
func closeAllTables(tables [][]*table.Table) {
	for _, tableSlice := range tables {
		for _, table := range tableSlice {
			_ = table.Close()
		}
	}
}
// Closes the tables, for cleanup in newLevelsController.  (We Close() instead of using DecrRef()
// because that would delete the underlying files.)  We ignore errors, which is OK because tables
// are read-only.