This was necessary because the rendering was always determining
which app item should have the class 'active'.
This was an issue with the 'Click Everywhere Test': at the beginning
of the script, it gets the jQuery element that matches all nodes
`a.o_app` in the app menu. When an app item is clicked, it re-renders
the whole app menu, so that older referenced nodes are detached from
the DOM. As a result, clicking on them no longer works, because it
never triggers the MouseEvent `click .o_app`.
This commit fixes the issue by rendering the whole app menu once.
When an item in the app menu is clicked, it dynamically changes
the `active` app.
Alexandre Kühn
95331042f1