Generate stacked transform features within a single table if max_depth is greater than 1

- As a user, I wish I could use Featuretools to generate stacked transform features within a single table. Currently DFS will not generate any stacked transform features within a single table, regardless of the setting of the `max_depth` parameter. Allowing for stacking of features within a table when `max_depth` is greater than one could be useful in some situations.

One potential use case of this would be to generate features that capture interactions between transform features. For example if we consider the case of trying to determine whether a given datetime falls during lunch time on a weekend, this could be generated by performing a boolean multiply on the features generated by the primitives `IsLunchTime` and `IsWeekend`. Currently only the boolean features from `IsLunchTime` and `IsWeekend` will be generated by DFS, but the stacked boolean multiplication feature will not be generated automatically.

Users can manually define these types of stacked transform features, but it could be beneficial for DFS to handle this.