nlutils VS ctl

This is cool! I've seen this C-with-templates used in the past with ".X" headers but haven't used the technique myself. Having something based on STL might help people to center on one library instead of constantly reinventing collections in C (which I've also done for some structures, and open sourced though I don't recommend using it: https://github.com/nitrogenlogic/nlutils).

I recall a few years back doing something like this implementing a binary heap just as a hobby project (https://github.com/Equationist/ctl/blob/master/pqueue.h). I was curious to see how unoptimized it was vis a vis the STL, and ran compiled equivalent test code for both my priority queue and the STL's C++ implementation, with just integers. I was kind of shocked to find that my implementation was like 30% faster when both were compiled at -O3 levels. Seeing this backport I guess there isn't anything fancy in the STL implementations, so it's less surprising that my naive implementation could be just as fast (or happen to be faster).