Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/13208] Add security issues to the final changelog
  [prep-release-3.1.0] Prepare Changelog
  [prep-release-3.1.0] Update version to 3.1.0

Conflicts:
	build/build.xml
	phpBB/includes/constants.php
	phpBB/install/schemas/schema_data.sql
	phpBB/styles/prosilver/style.cfg
	phpBB/styles/subsilver2/style.cfg