add version numbers to version index view
display newest version first
use bootstrap modal in file edit on discard
Merge pull request #913 from ontohub/500-newest_version_first

display newest version first
add download links to ontology version index
move modal functionality into discard()
use ontology.repository; repository does not exist

repository does not exist anymore (is not set in the controller),
so we'll access the repository through the ontology.
Merge pull request #919 from ontohub/hotfix_oops_repository_path

use ontology.repository; repository does not exist
Merge pull request #912 from ontohub/886-incremental_version_numbers

add version numbers to version index view
Merge pull request #914 from ontohub/828-use_bootstrap_modal_in_file_edit

use bootstrap modal in file edit on discard
refactor tarjan tree according to style-guide

Also objectify the class.
use SQL to fetch valid sentences for Tarjan Tree.
adjust tarjan tree uses across project

Use .for instead of .new.
remove invalid ontology_id/name constraint

Names in entity_groups are not unique.