Step 1: Refactoring tabsheet on NBM and introduce generic method to add tabsheet.tpl
On next commit, use of this new method in order to reduce # of link menu.
CSS friend don't hesitate to modify tabsheet css.
git-svn-id: http://piwigo.org/svn/trunk@1874 68402e56-0260-453c-a942-63ccdbb3a9ee
