Scale PET for other projects

1. If you want to select data from e.g. CMIP5 the plugin alows to select data where not all the required varibales exists.

See: https://www-regiklim.dkrz.de/history/6403/results/

2. Since we need to have orog variable for calculation, we have to make this work only for the projects listed here: https://www-regiklim.dkrz.de/databrowser/?start=0&variable=orog

3. We need to also handle datasets in nukleus where no altitude is present for the selected experiment: https://www-regiklim.dkrz.de/databrowser/?experiment=ssp370-gwl2k&institute=clmcom-hereon&product=ceu-3&project=nukleus&start=0&time_frequency=1day&variable=tasmin