Alternative base library

Would it not be easier to build on top of the generic [connection-string](https://github.com/vitaly-t/connection-string)?

@dwmkerr

It supports all the features needed here. And if you need any help with that - ask me, I can help you with that. Basically, it is already documented [there](https://github.com/vitaly-t/connection-string/wiki/Adapters).

Start with the linked connection-string adapters documentation and compare its supported features with mongo-connection-string. The issue names no files or tests; done would require an agreed migration scope and confirmation that the existing library behavior remains covered.

Written by the indexing model from the issue text.