Only redraw watchlist menu entries instead of entire menu when enabling/disabling a wiki/space/page.

If somebody were to use prototype Event.observe on certain menu actions, after choosing to watch/unwatch a space/page and re-drawing the entire menu (menuview.vm) the listeners would be lost. For example, I implemented "send page by email" in a lightbox which was hidden on page load. I used prototype to listen for a click on an 'email page' button on the print menu. When the entire menu is redrawn, the listener/s are broken, which is why I'm only redrawing the watch section of the main menu. It also slightly saves bandwidth. That is why I created a separate template to be used for drawing the watchlist section of the menu.