improved chemists by ensuring the same chemist object is always in play so that different formulas that update it state work together, also fixed a small bug with the loading of formulas by name
updated tests and chemist to reflect the mutability of type but not key
updated docs and moved the chemist aware module require to the base class
Merge branch 'feature/chemist-updates' into develop
Bumped version to 3.8.1 to prepare for release.
Updated CHANGELOG.md gemspec and readme heading for 3.8.1 release.
Merge branch 'release/3.8.1' into develop