minor changes to epi.c
started check_find_coordinates
prepared some basics of the find_candidate test
working on check_epi.c
going to remove the dumbbell part which is confusing, tol_band_width which is not well defined in terms of the size of the particle size and not in terms of millimetre units.
removed the tol_band_width part that was defined based on the longest size of the particle. This was probably useful for rods and colloids but it's not a general case and therefore removed at the moment.
todo: develop the find_correspondence_rods for the prolonged and rod-like particles