Add option to specify region by name

[alexoort]

Name and Institution (Required)

Name: Alex Oort Alonso Institution: Harvard

Describe the update

This update enables users to select their inversion area by typing a country's name. This makes running inversions over entire countries (for national emission tracking) far easier. Previous versions required a user to download a shapefile from an online database and then convert this shapefile into a statevector file through a jupyter notebook.

[alexoort]

Also includes changes from the previous pull request, which relate to incorporating plume data into the clustering algorithm

[alexoort]

Pretty sure that ruamel exactly copies the file's contents, so shouldn't be detected by git. Also have made suggested changes!