The old variable `prls` contains both snow and graupel which limits the
analysis of microphysical processes. In addtion, `pr` is merely the sum
of `prlr` and `prls` which can easily be computed in postprocessing.
Therefore, we switch to the proper individual precipitation rates.

Add the start year as variable to the template to capture future climate
scenarios. In addition, update the naming scheme that maps run IDs to
climate scenarios.

The script can either create a specific run scripts for a given
experiment ID, or all run scripts for the Monsoon 2.0 project.