added menu with links on every wiki page

I found more easy to have a menu at right side with all pages that going to pages tab each time (when wiki pages aren't linked). Inspired with the 'Quick Help' panel, here is initial idea for a wiki menu.

Here is a screenshot of the new menu:

I didn't remove the 'Pages' tab initially. This could be activated using a configuration on the project itself, for choosing Tab/Menu interface.