Added decoders for NumPy floats and ints.

However, they've been disabled -- not sure it's the best idea, as it reduces
the precision. This addresses issue #21, but I will mark that as wontfix.
Set up encoders for composability.
Updated to use composed encoders/decoders.
Added int and float convert functions.
Added content for linear regression.
Renamed functions to avoid collision with builtin 'all'.
Added encoder/decoder for Python dicts.

This addresses issue #22.
Added polynomial linear model class and wrapper func.
Converted LFE dashes to Python unders in attrs.

This addresses issue #23.
Added functions for instantiating classes.

This is just a wrapper for func-call, but its helpful as an API to provide
something that explicitly instantiates classes.
Added comment.
Added more content to linear model class section.