add SET_NAMEDCNT_MAX as per pairlist ref convention
replace isNULL with == R_NilValue in subassign.c
use DEC_NAMEDCNT in deletion of list elements with [<-
clean up EnlargeVector
misc cleanup in subassign.c
Merge branch '12-namedcnt-cleanup' into 13-newer-news
updates for recent mods in NEWS
fix curly bracket placement