add draw_elements/display_elements functions
def draw_faces(vertices, face_indices, normals=None, per_vertex_colors=None, per_face_colors=None, shading='flat', z_offset=0):
pass
def draw_edges(vertices, edge_indices=None, per_vertex_colors=None, per_edge_colors=None, z_offset=1e-3):
pass
def draw_vertices(vertices, per_vertex_colors=None, point_size=1, z_offset=0):
pass