Think carefully about automatic determination of data types

[dhuppenkothen]

We need to think a little more carefully about the automatic determination of data types.
At the moment, it assumes any column with floats is a continuous variable and any other column is a categorical variable. This may not always be the case (e.g. there could be a column if integers that should be used as a continuous variable or a column of say, three distinct float variables that designate categories).
We need to think carefully how to handle it, including not handling it at all and let the user pass in a dictionary of strings with the relevant data types?