Remove n-gons from .obj file

[josauder]

This issue goes hand in hand with #21 in order to produce completely portable .obj files.

As of now, there are n-gons in the .obj file (where n>4) which can be handled by blender but not by all visualizers. This also makes the scaling and direction of textures harder than if everything were triangles/rectangles. N-gons are created when the "cuts" are applied in building_generation.

[ZeroCool940711]

Hi there, I recently found this repository with this procedural city generator and it was exactly what I've been looking for a while now, I know this issue was made a long time ago and also that this repo hasn't been updated in a while but I would like to know if you managed to make the city generator save as an obj file. Is there any chance you could continue the development of this tool? Its pretty awesome and there are a few forks that had fixed some stuff but none of the forks have the issues open so it's hard to report things that are broken or get extra information on what works and what doesn't. Thanks for the time.