Use the cytoscape-context-menu library instead of previous bugged usage of context library

[Larcheveque]

https://github.com/iVis-at-Bilkent/cytoscape.js-context-menus

code to use the new library:

var instance = visu.contextMenus({
          menuItems: [
            {
              id: ''guillaume1'',
              content: ''guillaume'',
              tooltipText: ''guillaume'',
              selector: ".element1", //elements[elementId].id,
              onClickFunction: function (event) {
                alert("toto");
              },
              hasTrailingDivider: true
            }]});
	instance.appendMenuItems([
            {
              id: ''guillaume2'',
              content: ''guillaume'',
              tooltipText: ''guillaume'',
              selector: ".element0", //elements[elementId].id,
              onClickFunction: function (event) {
                alert("toto");
              },
              hasTrailingDivider: true
            }]);