Revised Math 3.5 Guide and GS with Math 3.5

I've gone through Laurent Balland-Poirier's excellent changes to the
Math 3.5 Guide and to Getting Started with Math 3.5 and edited some of
the English. Thank you Laurent for this work!

The amended files are in the Published folders on ODFAuthors and on
the Publications page of the wiki. I will soon update the link from
the Docs page on the website to point to the replacement Math Guide
files, and when I get a chance I will update the printed version at
Lulu.com.

--Jean