cc @findmyway @jonathan-laurent

Last week:

Some more work on batch implementation of environments at #146.

This week:

For now, we are putting batch environments on hold because it is still experimental and requires more digging in, in order to come up with a satisfactory solution that works on CPU, CPU multi-threaded, and perhaps most importantly on GPU. Right now, there are several issues that need to be resolved to make this package more coherent with respect to single environments. The goal for the next few weeks is to tie these loose ends and create a minor release before JuliaCon 2021, so that we at least have a coherent package with perfectly working single environments by then.