see dumux-repositories/dumux#648 TODO: * [x] Separate the properties for the Basics exercise ( !90 ). * [x] Separate the properties for the main file exercise ( !91 ). * [x] Separate the properties for the runtime parameters exercise ( !92 ). * [x] Separate the properties for the grids exercise ( !94 ). * [x] Separate the properties for the properties exercise ( !95 ). * [x] Separate the properties for the fluid systems exercise ( !96 ). * [x] Separate the properties for the coupling free and porous medium flow exercise ( !97 ). * [x] Separate the properties for the discrete fracture modelling exercise ( !98 ). * [x] Separate the properties for the biomineralization exercise ( !93 ).