* - False: this uses 'stupid OSI' house placement checking: part of the house may be placed here provided that the center is not in the region
* - True: this uses 'smart RunUO' house placement checking: no part of the house may be in the region
according to the text above, there will be still a nohousing-area.
anyway, i think the uneven ground is reason why i got these problems. maybe i change the height-check (HousePlacement.cs?).