restyle/relayout open items

[alexcjohnson]

Some remaining bits of cleanup not captured in #1999, as collected by @etpinard in https://github.com/plotly/plotly.js/pull/1999#issuecomment-329318166:

• those *AttrOverrides fields in base plot module objects. I feel with a bit more work and https://github.com/plotly/plotly.js/pull/1869), we won't need them at all.
• xaxis / yaxis asymmetries (as in mentioned in https://github.com/plotly/plotly.js/pull/1999#discussion_r138679149). Looks like there isn't a clear solution at this stage, but it's something we'll probably have to improve at some point.
• add some sort of edit convert method to component & baseplot modules to factor out colorbar pixel<->faction and axis range log<->linear logic similar to annotations/shapes/images convert_coords.js
• add a way to declare correspondence between attributes of different name across trace types (e.g. to generalize type edits involving pie traces, scattergeo lon/lat should correspond to x/y, ...)

[gvwilson]

Hi - this issue has been sitting for a while, so as part of our effort to tidy up our public repositories I'm going to close it. If it's still a concern, we'd be grateful if you could open a new issue (with a short reproducible example if appropriate) so that we can add it to our stack. Cheers - @gvwilson