Migrator().DropTable() ignoring schema from struct.TableName()

`Migrator().DropTable( &item{})` is not working properly when implementing `item.TableName()` and returning a name containing a schema, e.g:

```
type item struct {
Name string
}

func (i *item)TableName() string {return "test.item"} // specify schema name as "test"
```
calling `db.Migrator().DropTable(&item{})` generates the following SQL statement:

```
DROP TABLE IF EXISTS "item"
```
the statement is not using the full table name, the "schema." part is missing.

What is the proper way to find the table name for a struct? - I have seen different methods throughout issues and code.