Move S_hcs initialization to _init_arrays.
Make L a named, optional argument.
Add calc_K_l to multi. Also remove unused sanity_checks argument for K functions in common. Add cython extras for 3s K functions.
Put excitations stuff in a separate file and make it work with uniform_multi for L=1.
Make some expect... n arguments optional (default to 0).
Replace uniform with uniform_multi.
Remove s's and merge prereq functions in excite.
Pass on brute argument.
Fix brute check in pinv.
Fix brute calc_lr in mps_uniform and add an option to use it.