Additional weather data

[PGorzalka]

In a side discussion related to #1080 , @FWuellhorst @DaJansenGit and me were thinking about providing the soil temperature using the weather file. However, the current weather data reader from IBSPA does not support soil temperature. Similarly, it does not cover the longwelled radiation terms provided by the DWD TRY files.

I'd like to open this issue to have a discussion about if these data are needed and if some extension to the weather data reader is a good idea.

Benefits already discussed:

• no building-individual extra files needed for soil temperature

Potential drawbacks:

• soil temperature may actually be intended to be modelled individually for each building due to basement temperatures
• more complicated weather data handling

[FWuellhorst]

@PGorzalka I will check with IBPSA and see how they handle it. However, we could always extend TMY reader and add the soil temperature to the bus, if we agree on a format. I would like the concept, also for ground-source heat pumps o.s.