add ability to reload material without restarting container

[dougtoppin]

When modifying material the present container must be restarted to render the new material. It would be helpful to be able to load the new material without a container restart.

[patrick-nw]

I noticed this, too, and I agree. Thanks for working on this!

[dougtoppin]

Note that in the PR I sent it only copies the modules directory. I will likely add exercises to it as well before long. I just wanted to get this in the queue for comments in case I am way off base.