Updated UCR doc

I’ve spent a LOT of time over the last two weeks going through the current UCR document and working to clean it up in a variety of ways
- incorporated all the changes from the mainline branch (that Ivan and others have contributed since TPAC)
- Removed or combined various duplicate elements
- Moved around a bunch of content so it groups better
- Removed various contentious items – such as locators
- Fixed up a LOT of grammar issues
- Added a bunch of links and cross-references
- Rewrote many of the use cases to talk in proper language about formats vs. user agents.
- Removed some items that I couldn’t figure out how to resolve
- Added some EDITORS NOTEs about things still needing additional cleanup

I am now going to review all the open issues and see which one(s) can be closed based on this draft.

I will review the changes in as much detail as time provides tomorrow.  NOTE: I commented out things that I didn’t want to remove and/or to make it easier for folks to diff between my version and the mainline.  I tried very hard to not do anything that was (or could be considered) controversial – but I am sure I wasn’t 100% successful at that ☺.

Leonard