StringOps * could be improved by shortcutting on n=0 or 1

[RobinStephenson]

If n=0 or 1 no need to create builders etc

[RobinStephenson]

@rorygraves could you assign me this and #29 please :)

[rorygraves]

@RobinStephenson This one is assigned - the other i can assign (or you can assign once you accept the invite you should have just received.

[mkeskells]

@RobinStephenson can you update the status, labels and milestones, and refer to any PRs