Change "ab_" prefix to "split_"?

[henrik]

Would a "split_" prefix be better than "ab_" for methods like "ab_test" (so "split_test" etc), since there can be more than two options? Since we might release a 2.0 with other breaking changes, this might be a good time to also make this change, if it makes sense.

Wikipedia gives the impression that the term "A/B testing" only covers two alternatives.

I don't feel strongly about this – I think "ab_" is quite acceptable even if it might technically be a bit incorrect – but I thought I'd bring it up while 2.0 is in the works.

cc @joakimk

[andrew]

I don't have any strong feelings either way, split_ might be more likely to clash with other methods the user defined like split_name for example but it's an edge case either way.