newRPL - Updated to build 1510 [official build remains at 1487]

[John Keith]

I agree that AND is rather non-intuitive for concatenating lists, on the other hand CAT makes me think CATalog more than conCATenation. Haskell uses ++ which I like but I doubt that the parser could handle it. Also potentially confusing since ++ means increment in C.

I also like the idea of FORSTEP/STARTSTEP but I'm not sure which syntax I prefer.