API support for type override

[dorisjlee]

Occasionally, there might be mistakes in the data type that is automatically detected in Lux, we should support the ability to let users override the inferred data type and persist this inferred setting throughout the session (even if the metadata has to be recomputed again).

[dorisjlee]

For example, in the real estate data, the Year and Month attributes are detected as temporal, but they are not true datetimes, but a sequence of ordered months and years. User-defined type overriding would be useful here.

df = pd.read_csv("https://github.com/lux-org/lux-datasets/blob/master/data/real_estate_tutorial.csv?raw=true")
# df["Year"] = pd.to_datetime(df["Year"], format='%Y') 
# df["Month"] = pd.to_datetime(df["Month"], format='%M')

[dorisjlee]

Pending documentation and tutorial on data types before we close the issue.