cv.tex: Add a "FLOSS contributions" section

cv.tex: Add a "FLOSS contributions" section

To add more background for projects where I've played an important
role for several years.  I think these entries are more relevant for
software positions than the "System administration" section, so I've
put them first.  I've also shifted the old "Software" entries up into
the new section, since the new entries are basically highlights from
the raw project lists.

I've dropped the font size to 11pt to keep everything on two pages.