open-forcefield-group/openforcefield: Version 0.0.2

This version: Finishes migration of many tools from smarty to openforcefield Removes outdated examples and data Adds support for tip3p water and constraints, tests for the same; adds water monomers Extensively updates documentation Updates Jupyter notebooks Makes some fixes to chemical environments Fixes a bug where vdW parameters for mixtures consisting of multiple references molecules could get scrambled (and adds a test for this) Fixes a typo in descring the SMIRNOFF format (formerly SMIRFF) and finishes name change from SMIRFF to SMIRNOFF Adds an example of generating a mixed force field for a protein-ligand complex (AMBER protein force field, SMIRNOFF ligand