DataModelWrapper and ConfigWrapper add methods now return self, allowing chaining.
Reworked DataModelWrapper to take 4 values per attribute and also automatically number the features with an auto incremental value.

Added True and False to string_aliases, and renamed that file to boolean_aliases.

Added cleaner tests for trimming and missing values.
Finished the cleaner tests.
Fixed a bug with the cleaner in which categorical numerical features were tracted in a wrong way when applying nan_treatment.
Add 'find_numerical_features' method to DataModel.
Tested find_numerical_features.