a FOLD object with vertices_coords, faces_vertices, and if vertices_faces does not exist it will be built.
an array of 2x3 matrices. one per face.
a new set of vertices_coords, transformed.
Given a FOLD object and a set of 2x3 matrices, one per face, "fold" the vertices by finding one matrix per vertex and multiplying them.
a FOLD object with vertices_coords, faces_vertices, and if vertices_faces does not exist it will be built.