Use <a> instead of <a href="#"> for JavaScript click events

Use <a> instead of <a href="#"> for JavaScript click events

* No status line with URL and "#".
* No new tab on middle click.

a { cursor: pointer; } ensures to have a pointer as mouse cursor on hover.

tabindex="0" ensures to have a normal tab order.

role="button" according to
https://www.mediawiki.org/wiki/Accessibility_guide_for_developers

Change-Id: I5903901752ffb52e778f3582c7da0f820dc305c8