Changes to modular_template.html's navbar

[FoFFolo]

Added a sticky attribute to the navbar so if the canvas is bigger than the screen, you can push the actions in the whole page. Also the actions have been replaced to hyperlinks(a element) to button in order to avoid reloading the page at each press and not bring the page at the top after each action.

[rht]

Tested and it worked. And the sticky bar is an improvement.

[rht]

Merged, thank you @FoFFolo.