Create method for Models and Schemas that allow adding/updating Fields/Columns properties

[pedroaugustosmribeiro]

Currently there is update_columns for pandas.DataFrameModel, but that completely overrides the original column definition, substituting by a new one.
Suppose I have a Base Model for validation only, and I want to compose a Child Model that will only extend the base one by adding parsers for pre-processing/cleaning my dataframe columns, with specific parser funciont(s) per column, I may have a dict with column name as key and another dict with column property to add/update (aka update_kwargs, like {'parsers': [parser_fn1, parser_fn2, ...]}, so that the Child Model can do more than just validating raw data.