Option to run with perfect foresight and scenarios

[HauHe]

A option to run the model under perfect foresight while providing scenario options like in the myopic set up with limited foresight would facilitate to have one base case/reference scenario of a model and then run scenarios without creating each time by hand a modified new model file/set of csv files.

[HauHe]

This could be a work around for the issue that we discussed in ECEMF regarding how to keep track of general model updates and scenarios settings.
Don't have time currently to look into this but perhaps once my workload has a bit normalised we could discuss this @willu47