DataFrame to_dict method should also provide orient parameter (like to_json)
Hello,

it will be nice if `to_dict` method could provide same `orient` parameter as `to_json`.
For example when `outtype='split'` we get same results as `outtype='series'`.

I also noticed that `df.to_dict(outtype='split1234')` is understood as `df.to_dict(outtype='series')` which is quite strange but `df.to_dict(outtype='a1234')` raises `ValueError: outtype a1234 not understood` which is a correct behavior

Kind regards

Femto
