Interface to assign ID with a query after insert (like OracleDialect)

Hi, I noticed that in the former version of Oracle Dialect the automatic fetch of a generate id was missing.
I created a new Interface for the purpose: `TargetQueryInserter`

Here is an Example of usage:

	var obj struct {
		Id int64
	}
	var t = dbMap.AddTable(obj)
	t.SetKeys(true, "Id")
	t.ColMap("Id").GeneratedIdQuery = "SELECT sequence.currval FROM DUAL"