Consistently prefixes Functions with '_.'

[LewisJEllis]

Fixes #170

[jeromew]

@LewisJEllis great thanks. Have you already discussed with @vqvu on what is the best strategy to keep 3.0.0 in sync with 2.x ? 3.0.0 should probably be regularly rebased on top of 2.x.

We already have a few commits lagging from what I see and we'd better address this workflow before the thing becomes unmergeable.

[vqvu]

I don't think a rebase is required; a rebase would break anyone trying to work on 3.0.0. I was planning on someone just doing a git merge master once in a while (doesn't have to be all the time to keep the tree clean) and fixing anything that's broken.

[jeromew]

I was thinking about '3.0.0' like a shared PR where we would rebase it regularly so that it has a clear log footprint (the tip of 2.x + modifications). Do you really think many people are 'working on 3.0.0' apart from the usual suspects ?

But I agree that once it is published it is not a good thing to rebase it. maybe if we need a cleaner log footprint we can do a 3.0.1 branch or whatever.