Add KPI block for thermal zone KPIs

[FWuellhorst]

We have automatic integration for energy values for heating (gain) and cooling (loss), as well as comfort values in the ROM model. However, the graphics are rather clumpsy. Also, only internal, heating, and air exchange balances are created. This feature adds a single block and adds floor, roof, windows, and outer walls into the energy balances for a full picture on everything that happens in the zone. @TobiasSpratte: Could something like this also be used for SPAWN? Should be possible for AixLib HOM at least.