Feature/build diff

[kent-white]

• In DiffStep enum I included the object in .delete. This is so that we can keep track if we are inserting and deleting the same object or different object. You may be able to do this without the object in delete as @ianterrell thought.
• This implementation of processDiff doesn't handle a combo of insert/delete on the same object at the same index, it will will just leave those steps as is. I commented on the line where that may be handled (163).

[ianterrell]

It looks to me like buildTable and buildDiff are working on equality. Then processDiff looks for updates by checking identifiedSame.

Would this whole thing be simpler if that were reversed? If buildTable and buildDiff worked off of identifiedSame and then processDiff checked equality (perhaps with metadata tracked by buildDiff)?

[ianterrell]

Stylistically I believe we prefer a space after comment markers, before the comment.

//not like this
// but like this

[ianterrell]

Thinking through it, I think we need our extension to be limited to collections whose indices conform to BidirectionalIndexType, and then we should only be using predecessor() and successor() instead of advancedBy(). Thoughts?

[ianterrell]

I think maybe after a few more changes we're ready to rebase and merge it in. Probably only worth 1 commit? Thoughts?