[ticket/11966] Merge branch 'develop' into ticket/11966

PHPBB3-11966
[ticket/12060] Update docblock for core event due to addition of another var

PHPBB3-12060
[ticket/12009] Move valid extensions in tests to correct dir structure.

PHPBB3-12009
[ticket/12009] Fix functional tests.

PHPBB3-12009
[ticket/12009] Update functional test to check for invalid extensions.

PHPBB3-12009
[ticket/12060] Use $sql_ary instead of $sql

PHPBB3-12060
[ticket/12060] Refactor u_action in the events that use it

PHPBB3-12060
[ticket/12060] Update the docblock comments in acp core events

PHPBB3-12060
[ticket/12060] Change @since in event docblocks

PHPBB3-12060
[ticket/12060] Fix u_action comments in docblocks

PHPBB3-12060
[ticket/12009] Prevent user from enabling invalid extension through direct URL

PHPBB3-12009
[ticket/12060] Correctly label alpha versions in event docblocks

PHPBB3-12060
[ticket/12063] Use CSS to replace valign=top

PHPBB3-12063
Merge remote-tracking branch 'vsephpbb/ticket/12063' into develop

* vsephpbb/ticket/12063:
  [ticket/12063] Use CSS to replace valign=top
  [ticket/12063] Remove obsolete valign attributes from tr tags
Try running unit tests on HHVM
[ticket/12060] Rename event from append to after in acp_bbcodes.html

PHPBB3-12060
[ticket/12060] Use separate template event for acp user signature posting buttons

PHPBB3-12060
[ticket/12060] Further clarify/fix a var in acp_bbcodes_modify_create event doc block

PHPBB3-12060
[ticket/12060] Add num_predefined_bbcodes to display_custom_bbcodes_modify_sql

event

PHPBB3-12060
[ticket/12060] Rename event in message parser to modify_format_display_text_after

PHPBB3-12060