introducing repository settings controller
beginig the subnavigation
Merge branch 'staging' into 585-repository_settings_page
make subnavigatione method more flexible
using flexible subnavigation method
change position of the elements of the settings elements
move permissions tab into the settings subnav
remove edit and delet buttons
Maybe fixing 576
introducing entity-groups for using it in trees
implement tarjan for grouping the entities
change EEdge to connect entity groups and not entities anymore
using tarjan
tests are green
Merge branch 'staging' into 748-using-tarjan_for_entitytree

Conflicts:
	app/models/ontology.rb
fixing test
correct indentation
correct english
improve determine_group_name
comment spliting for later understanding