[FEATURE] Refactor & recolor Modul-Menu (Bootstrap)

Base module menu on Bootstrap less variables navbar-inverse.
First step on roadmap to a backend scaffold without ExtJS ('Flat').

Since the module menu link section must be taller for fingers
and touch (long time goal: 44px height):

+ Moves module menu "User tools" section into the Topbar.
User tools will be in dropdown-menu at User (#62166).

+ "Help Center" section will be moved from module menu
to Topbar (#62338).

Colors module menu, topbar and doc-header will be adapter.

Resolves: #62353
Related: #62166
Related: #62338
Releases: master
Change-Id: I5912508efa1fa8d378afeb0722e7a00be0b86f71
Reviewed-on: http://review.typo3.org/33399
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Ingo Pfennigstorf <i.pfennigstorf@gmail.com>
Tested-by: Ingo Pfennigstorf <i.pfennigstorf@gmail.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>