added package ExteriorExtensions

[LukeOeding]

Adding package under review at JSAG.
I've corrected some spelling errors.

[LukeOeding]

fixed spelling errors

[d-torrance]

Thanks for the contribution!

Don't forget to add the package to the file M2/Macaulay2/packages/=distributed-packages.

[d-torrance]

There are some conflicts in the =distributed-packages file with some other packages that have been added recently. If you click on the "Resolve conflicts" button, you should see something like:

<<<<<<< master
ExteriorExtensions
=======
IncidenceCorrespondenceCohomology
ToricHigherDirectImages
Brackets
>>>>>>> development

Delete the <<<'s, ==='s, and >>>'s and then commit to fix the conflicts.

See also https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/addressing-merge-conflicts/resolving-a-merge-conflict-on-github for more info.

[d-torrance]

You should add a few tests (using the TEST keyword) to make sure that your code is doing the correct thing