vertical metrics: shall we match the other versions of Roboto or start from scratch?

I don't think this version of Roboto has the same vertical metrics when compared against v2 and the other VF.

If we end up matching the older versions, the hhea and typo will have differing values. If we start from scratch, we can ensure that all 3 sets are in sync.

Imo it may be a nice idea to use the same typo metrics as the older releases but make sure the hhea metrics match. This way we get the best of both worlds, albeit it will be different for OS X.