Merge pull request #1 from hallvors/master

a few more ID attributes
Clarify that header names are compared in a case-insensitive manner
Instead of Workers monkey-patching XMLHttpRequest, recognize Workers as a part of the architecture.

This removes the XMLHttpRequest base URL, document, origin, and
referrer source concepts and replaces them with easier to follow rules.
Make the document response entity body null in a worker environment and in that same environment ignore setting responseType to "document"
Update logo and encoding reference
Move defining Document to the constructor
Define URL parsing properly and define user/password arguments the way Gecko implements them, via the URL. Fetch will need to tie the loose ends together.
Editorial: rename user to username for consistency with URL.
Minor cleanup around URL handling.
Use concept-document-origin and remove a silly comma
Remove the terminate send()/abort() concept in favor of using the error flag.

Fixes https://www.w3.org/Bugs/Public/show_bug.cgi?id=19470
open() cleanup.
Fix indentation.
Simplify wording in introduction as it was largely bogus.
More cleanup. (Much less "terminate these steps".)
Always combine headers using ", " rather than allowing multiple ways. Also trim trailing whitespace.
Requirements on proxies and cookies don't belong here. They are relevant to fetch in general.
Describe what happens when a data: URL fails to parse and use network error as handling rather than any particular status code.
Remove the Streams API reference as that API is not agreed upon. Have CORS point to W3C TR while Fetch is still being developed.
Remove remaining bits of Stream.