got rid of unused argument to kernel_weighted_sum_np
in the process of adding new feature to kernel_weighted_sum_np: scale weights by h
generalized nn seems to be working w/ npcdens, but need to compare to old builds to be 100% sure
some small tweaks still required for adaptive nn
npcdensbw calls the old c code for cv.ls + nn bws
now compiles with -std=c99 -Wpedantic without warnings