Avoid hardcoding project root folder

[hturner]

Currently, project root folder is hard-coded e.g. in setting the environment variables (see #103).

This needs to be avoided so the same scripts can be used on GitPod and in other contexts. See #103 (comment) for likely solution.

[hturner]

#158 has removed the hard-coding, so this is fixed for Gitpod and should be general enough to fix for the local setup from a zip file (untested).