Updated versioning strategies doc

I decided to create a revised versioning strategies document that has
been renamed versioning: compatibility strategies.  The goal was to make
the document shorter and more to the point.
 
The main changes are:
- removed about 4 pages of material on motivation etc. so now down to 14
pages print preview
- updated the introduction to hit the 3 main messages right up front
- moved the version identification strategy section to the earlier
versioning strategies document
- Promoted the incompatible, backwards and forwards compatible sections
to first level sections.
- numerous updates to the rest of the document.
 
The docs are at
http://www.w3.org/2001/tag/doc/versioning-compatibility-strategies
http://www.w3.org/2001/tag/doc/versioning-compatibility-strategies-20070
920.html
 
http://www.w3.org/2001/tag/doc/versioning-compatibility-strategies.xml
http://www.w3.org/2001/tag/doc/versioning-compatibility-strategies-20070
920.xml
 
I expect that these will be revised as per Dan and my action items.
 
Cheers,
Dave