Prepare move to other licence. For the moment all answers for licence
upgrade were not yet received. So we prepare for GPL by uniformizing
licence text keys to GPL-3+. Will move later to AGPL if all answers are
positive.
Merge remote-tracking branch 'origin/3.3' into develop

Conflicts:
	COPYRIGHT
	htdocs/core/tpl/freeproductline_create.tpl.php
	htdocs/core/tpl/predefinedproductline_create.tpl.php
	htdocs/install/mysql/tables/llx_c_availability.sql