[css-position-3] Rewrite Completed

Hi everyone,
Tab and I finished a complete rewrite of the CSS Positioning Level 3 spec 
today. There are no new features, but we integrated it with the current state 
of css-align-3 and css-writing-modes-3 and referenced css-display-3 and 
css-sizing-3 where appropriate. We left the old abspos layout chapter intact 
as a reference for now: there should be no change in behavior in the default 
writing-mode + self-alignment case.

We'd like to publish an updated Working Draft after everyone has a chance to 
review and flag any obvious errors.

I'm hoping by tomorrow the draft server will finish rebuilding [1], but for 
now you can view the draft here:
   https://lists.w3.org/Archives/Public/www-archive/2020Apr/att-0006/Overview.html

[1] https://drafts.csswg.org/css-position-3/

Thanks~
~fantasai