Also inlined are: length and reverse, endp and identity are expanded,
the former to throw an error only when safety >=1.
There is an unused heap sort in the code too, but I can't see any gain
here, as the memory requirements are virtually the same. The
quick-sort is non-recursive and uses a tiny stack ~ log_2(n). I have
to read up on what stable-sort is supposed to be.
More to follow. Feedback appreciated. Notably, sort is likely the
biggest inline we would ever consider, and its impact on code size
might be arguable. But it certainly pays off in performance.