Streamline and Refactor external libs

[ppalmes]

@JuliaRegistrator register()

[JuliaRegistrator]

Registration pull request created: JuliaRegistries/General/1069

After the above pull request is merged, it is recommended that a tag is created on this repository for the registered package version.

This will be done automatically if Julia TagBot is installed, or can be done manually through the github interface, or via:

git tag -a v2.1.0 -m "<description of version>" 2bc3aa0fde65ef0ee2504d252c3fc29125fa946f
git push origin v2.1.0