v2.1.0

This release fixes a number of bugs that arose since v2.0.1 as well as documentation and a CI.

Changes

1. Merged in patches #134 @mxschmitt.
2. Merge in patches #135 & #136 by @hasparus.
3. Fix for #139 implemented by @VirtualDOMinic.
4. Added CONTRIBUTION.MD by @kiraarghy.
5. Added CI including prettier, eslint, and tests using sail.ci.

Thanks to everyone who contributed