Fix jump links

* only add jump links if the side menu is used
* only add jump to H2s

Signed-off-by: Timo Dörr <timo@latecrew.de>
Fix main content margin to bottom

* Add +10px as additional margin to fix display if no
  heading is used (which has its own margin)
Insert scripts from navigation.md into the DOM
Merge remote-tracking branch 'upstream/master' into h3_navigation

Conflicts:
	js/basic_skeleton.js (manually fixed)