Licence GPL 3.0/en

The VLE environment changes its license!

The chosen license is the updated version of the GNU General Public License. VLE is also distributed under the GPL license version 2.0 to the GPL license version 3.0. The future versions of VLE (0.5.x) will thus be under this new license.

The changes were made from tags on the following repositories:
 * vle.git 87b40bd2d443bd52ee1f08eb8db6019a31f6ec4d
 * eov.git ea31de3c65cdd3ac40bdda6909de01924761867c
 * examples.git 54c75eea14cc2434c6e41e918a10beda6fb8aa1f