Merge pull request stackbuilders#121 from stackbuilders/release-20200416

Release 20200416

Merge pull request stackbuilders#117 from stackbuilders/release-20200211

Release 20200211

Merge branch 'tutorials' into release-20180613

Merge branch 'tutorials' into release-20170810

Merge branch 'tutorials' into release-20170720

Merge pull request stackbuilders#56 from stackbuilders/release-20170720

Release 20170720

Merge branch 'tutorials' into release-20170712

Haskell Generics tutorial (stackbuilders#40)

* Write the generics tutorial
* Address Leticia's feedback
* Address Nathan Lander's feedback