[ticket/12024] Template event overall_header_content_before

http://area51.phpbb.com/phpBB/viewtopic.php?f=111&t=44959
http://tracker.phpbb.com/browse/PHPBB3-12024

PHPBB3-12024
[ticket/12024] Replace newline
PHPBB3-12024
[ticket/12024] Update events list
PHPBB3-12024
[ticket/12024] Correct the 'since' information in event list

PHPBB3-12024
[ticket/12024] Add new line

PHPBB3-12024
Merge pull request #1878 from blitze/ticket/12024

[ticket/12024] Template event overall_header_content_before