Data structure for stellar properties
Currently, some properties, such as mstar, are read from ProDiMo.out, others are not.
Make this more consistent, e.g. read everything relevant. It might be useful to have a DataStar Class for this.
This one could also include the Spectrum. To be backwards compatible, one can simply implement property methods that provide information from the DataStar structure instead of directly from Data_ProDiMo.