[ticket/13203] Add method for byte by byte comparison to drivers helper

PHPBB3-13203
[ticket/13203] Use string_compare method in passwords drivers

PHPBB3-13203
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/13203] Fix passwords manager tests
  [ticket/13203] Use string_compare method in passwords drivers
  [ticket/13203] Add method for byte by byte comparison to drivers helper
[prep-release-3.1.0-RC6] Add migration for 3.1.0-RC6
Merge branch 'develop-ascraeus' into develop

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