Merge branch 'prep-release-3.1.1' into develop-ascraeus

* prep-release-3.1.1:
  [ticket/13271] Disable CC sender feature for anonymous users
  [prep-release-3.1.1] Add 3.1.1 CHANGELOG
  [prep-release-3.1.1] Add 3.1.1 migration file
  [ticket/13263] Make sure default style exists and clean up code
  [ticket/13263] Only install/set prosilver if no style available
  [ticket/13263] Use prosilver as default style if user's style doesn't exist
  [ticket/security-164] Correctly format page_name
  [ticket/security-164] Sanitize all global variables in symfony_request class
  [ticket/13248] Use functional framework login method in tests
  [ticket/13248] Correctly pass provider name
  [ticket/13248] Always use provider collection for getting provider
  [ticket/13248] Allow specifying different auth provider in provider collection
  [ticket/13248] Use auth provider collection for getting provider
  [ticket/13262] Mention htaccess file when updating from 3.0 to 3.1
  [ticket/13267] Update Automatic Update instructions to include vendor directory
  [ticket/13268] Properly append ternary result in get_existing_indexes()
  [prep-release-3.1.1] Update version number to 3.1.1

Conflicts:
	build/build.xml
	phpBB/includes/constants.php
	phpBB/install/schemas/schema_data.sql