parametric house

Made the "doghouse" completely parametric to be able to use it for creating a garden house also.

Parameters:
- breite = width
- laenge = length
- unterbau_balken_breite = substruction beam width
- unterbau_balken_hoehe = substruction beam height
- platform_hoehe = platform height
- support_balken_breite = support beam width
- support_balken_hoehe = support beam height
- hoehe = wall height
- wand_staerke = wall width
- dachneigung = roof pitch in degree
- tuer_hoehe = door height (