Tutorials for using the GPU-accelerated Python API

[NikoOinonen]

I want to add some tutorial type documentation for how to use the OpenCL Python API for running simulations, especially from the point of view of how to run a massive number of simulations like we have done for our machine learning training.

At least the following should be documented:

• Add tutorial for the AFMulator #268
• The AuxMap descriptors
• The Generator that combines the previous two