Acepace remove future

[acepace]

This removes some dead code, starting with the low hanging fruit mentioned in #4817

Playing around with the zip imports but it's not PR ready yet.

[gvwilson]

@emilykl can you please have a look at this as part of the plotly.py repo cleanup work?

[acepaceNS]

Can anyone check on this?

[gvwilson]

Thanks for the PR @acepace - we're hoping to merge #4978 this week, which goes further toward removing out-of-date code in order to shrink the plotly.py bundle size. If you have time to look over the changes in ./codegen and ./_plotly_utils I'd be very grateful for feedback. Thanks - @gvwilson