bug #4014 :  Load now the groups per page in the filtering panel and maintain them in a cache so that the pagination can ran more faster. Some bugs require to be fixed in the groups cache management with the filtering panel
bug #4014 :  Fix the bugs in the groups cache management and externalize it into a dedicated object. The selection of all groups is also rewritten as they can be not all yet loaded
bug #4014 :  Add localized label of 'next groups' and fix a little bug with the rendering of the next groups link
bug #4014 :  Modify the pagination mechanism: now the pagination is operated directly in the DAOs. So, a search criterion on the pagination is defined and a new list, to represent a list slice, is introduced to carry the search results matching the pagination criterion (the user profiles or the user groups)