Eliminated the lib.frame_order.iso_cone.populate_*() functions.
The populate_1st_eigenframe_iso_cone() function was unused and incorrect, so it was deleted. The
contents of the populate_2nd_eigenframe_iso_cone() function have been shifted
compile_2nd_matrix_iso_cone() as a separate function is unnecessary. This now matches all the other
lib.frame_order modules.
