ACTION-1729: Diff marked version of Text Alternatives document

As per my action item today, I have produced a diff marked version [1] from
the last public working draft [2].  That draft was published just prior to
HTML5, and the majority of its content was put into HTML5 verbatim in
section 4.7.1.1 [3]

Unfortunately, there are SO many changes that the diff marking is largely
useless.  But maybe someone can get something out of it.

[1] https://w3c.github.io/alt-techniques/alt-techniques-diff.html
[2] http://www.w3.org/TR/2014/WD-html-alt-techniques-20141023/
[3] http://www.w3.org/TR/html5/single-page.html#alt

-- 
Shane McCarron
Managing Director, Applied Testing and Technology, Inc.