Dynamically source variables from install.conf each time the app is opened

[bantucaravan]

Variables from install.conf are currently manually hardcoded into the wrap files upon installation (for example here: https://github.com/telamonian/jupyter-app/blob/2549f59572479aa3bcf40d87771af0fa96523d2b/install#L223).

To allow changing virtual envs (for example), I would like to source the variables in the wrap scripts each time app is opened. Is there any reason why this is not done currently?