Change footnote representation

This commit tweaks the source code for footnotes. It starts them on a
new line (with a comment eating the previous newline) and adds a space
and comment to close them. This representation makes line-wrapping work
better and makes the footnote self-contained in git.
Merge branch 'master' into ema

This commit changes the way footnotes are represented in the
latex souce code to play better with emacs and git.