Saving clusters takes forever about cytopy HOT 1 OPEN

Hi @jfgonsalves, it is currently single threaded. Part of the problem is that I use Mongoengine, which registers connections globally (https://mongoengine-odm.readthedocs.io/guide/connecting.html). It was a long time ago now, but if I remember it was giving some horrible warning messages with multiprocessing.

With the new version, I want to have a user-defined config file for connection strings, and connections can be created and destroyed within each child process. This is a big refactor though. I'm very very close to finishing my thesis, so promise this will be getting my attention soon.

from cytopy.