Bug in calc.ScenarioWeather: incorrect selection of rip

[dschlaep]

"I selected the lowest variant (rXi1p1) to download for each rcp--but for EC-EARTH, there several variants that do not exist for all rcps, and the code so ended up downloading different variants for some rcps. I realized this and downloaded the lowest common variant (r8i1p1) for all rcps and added those files into the appropriate folders. However, rSFSW2 still selected the lowest variant (as opposed to the lowest common variant) and found that it was not available for all rcps." (reported by @racheopod)

e.g.,

Error in calc.ScenarioWeather(i = i, ig = ig, il = il, gcm = gcm, site_id = site_id, :
'calc.ScenarioWeather': input file(s) for model "EC-EARTH" and scenario(s) "historical"/"rcp26"/"rcp45"/"rcp85" not available for required variables: "pr"/"tasmax"/"tasmin"

Todo:
--> fix code so that the lowest rip, but one that is available for every variable, is selected