Add obj format export option

[karimnaaji]

Add an option to export model to OBJ format, this option can be useful to unwrap UVs in a 3d software package like Blender, perform mesh cleanup or any other mesh manipulation.

Depends on #57

[thinklikeanarchitect]

Hi, actually I have done this in Unity beforehand. I have already heard about your asset. I wonder if its possible to search for a location in runtime and then select a region with dragging and import it with building if some exist.