Use Bootstrap grid for arrangement of navigation items.
Shorten the characters of the current page title in DocHeader to
title length defined in user settings or default to '50'.

Resolves: #79849
Releases: master
Change-Id: I0825818cd961b8bb7f928cb1389537506d5ed40b
Reviewed-on: https://review.typo3.org/51831


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Joerg Kummer <service@enobe.de>
Tested-by: Joerg Kummer <service@enobe.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>