Prep for big editorial cleanup: move Ruby
Prep for big editorial cleanup: move "User Interactions" into place.
Prep for big editorial cleanup: non-normative tag replacement
Prep for big editorial cleanup: element-dfn -> concept-element
[e] (0) Big editorial cleanup. No normative changes.

git-svn-id: http://svn.whatwg.org/webapps@8634 340c8d12-0b0e-0410-8428-c7bf67bfef74
(cherry picked from commit 5984a04172ba296b9875a6dc7ad224dfe601ed92)

Conflicts:
	complete.html
	index
	source
Post fix-up for big editorial cleanup

Followup cleanup:
* Hid Workers explainer
* Reverted a bad merge on a few floating->local changes in terminology
* Nav element example was double-included (removes another FORK from our
doc)
* Accidentally dropped the code,var,samp,kbd,sub,sup,i,b,u,mark
element's aria meta-data
* Missed removing the note to Erika
* Bad merge in focus-chain section

Editor's Notes:
* [CORS] reference is now [FETCH]; related prose refers to WHATWG Fetch
specification (it was already a WHATWG reference prior to this change,
but under the term "CORS")
* Removed FORK at Line 9369 since the previous commit pulled out the
material that necessitated the fork.
* Main & Div were out of alignment with WHATWG, now they are again
aligned (this was not in Ian's change).