Multi exp interface

[dtebbs]

Exposed some more fine-grained scalar muliplication operations.

[madars]

This looks good! We have a more generic interface for multi_exp, i.e. exposing the two iterators for vector start and end, rather than start + length. Maybe we can do the same here?

[dtebbs]

We have a more generic interface for multi_exp, i.e. exposing the two iterators for vector start and end, rather than start + length. Maybe we can do the same here?

Thanks for the comments @madars. Yes, the interface with iterators is better. I was originally concerned with keeping the change minimal, but iterators makes more sense - I'll do that.