[ticket/12594] Remove @package tags and update file headers

PHPBB3-12594
[ticket/12594] Update footer credit lines

PHPBB3-12594
Merge remote-tracking branch 'upstream/develop-ascraeus' into ticket/12594

Conflicts:
	phpBB/docs/hook_system.html
Merge remote-tracking branch 'upstream/develop-ascraeus' into ticket/12594
[ticket/12594] Replace phpBB Group with phpBB Limited

PHPBB3-12594
Merge pull request #2507 from Marshalrusty/ticket/12594

File headers, credit lines, etc. should reflect updated legal info

* Marshalrusty/ticket/12594:
  [ticket/12594] Replace phpBB Group with phpBB Limited
  [ticket/12594] Update footer credit lines
  [ticket/12594] Remove @package tags and update file headers