Integrate One-Hot Encoding

[KD335]

Integrate one-hot encoding into the front end such that the code that performs on-hot encoding is silently added to the generated code after y values are selected and before the data is split into train and test sets. This is similar to how the code for cleaning the data is silently added.

[john-coffman]

Is_catagorial.py will return a boolean on if the data is categorical or not