When working on issue984 I worked my way through some parts of the hm landmark factory. I observed that several functions have a parameter "m" and whenever they are called, they get the global "m" parameter which they have access to anyway. I don't know yet whether this could have an influence on the performance, but I believe avoiding to pass that parameter makes the code more readable.

Maybe there are more things we could clean up when addressing this change. For example, I was irritated by the recursive design at first, and maybe doing the same thing using loops could be an alternative. (Not sure whether there are limitations that make recursion necessary here, but I can try to figure this out.)