Allow other folders

[elinw]

Thank you for taking on this task! I can't wait to try it with my students and for myself.
One suggestion I would like to make is that create_simulation_folder() provide the option of creating the folder in a specified location. For example, in RStudio, it is common to use projects, and I would want to make a separate project for each set of different things that I did in a separate project. Each project would represent a different working directory. It could still default to the home directory so existing behavior remains the same.

If you want, I could send you a pull request for this.