As started with efe9ecf.

Note that Math does not have its own menu entry and is only available from the
LibreOffice starter menu. That's why we're pointing to it.

Conflicts:
	wiki/src/doc/about/features.fr.po
	wiki/src/doc/first_steps/upgrade.pt.po
	wiki/src/support/known_issues.de.po
	wiki/src/support/known_issues.fr.po
	wiki/src/support/known_issues.mdwn
	wiki/src/support/known_issues.pt.po

Support running language_statistics.sh from the root of the repository too, and error out if it's not run from a supported place.

Conflicts:
	config/chroot_local-includes/usr/local/bin/tails-activate-win8-theme

Conflicts:
	config/chroot_local-includes/usr/local/bin/tails-activate-win8-theme

Closes https://labs.riseup.net/code/issues/7401 with the associated gnome-theme-windows8

Conflicts:
	config/chroot_local-includes/usr/local/sbin/tails-prepare-win8-theme

Conflicts:
	config/chroot_local-includes/usr/local/sbin/tails-prepare-win8-theme