Get rid of white lines on a mesh consisting of coplanar planes

So basically my mesh that I create in qubicle contructor and export as a .obj displays in game with white lines across the mesh outlining each voxel that makes up the object. Is there a way to fix this? alternatively, is there a way to get rid of the coplanar parts of the mesh to both reduce vertices and most likely fix this problem (probably using blender or something)?