[ticket/11922] Drop all keys before trying to delete columns to avoid issues

On MSSQL columns that have an index can not be dropped.

PHPBB3-11922
Merge pull request #1857 from nickvergessen/ticket/11922

[ticket/11922] Drop all keys before trying to delete columns to avoid issues
[ticket/11241] Add dropdown control button.

PHPBB3-11241
[ticket/11241] Consolidate topic actions into "Topic tools" dropdown.

PHPBB3-11241
[ticket/11241] Use DEFINE for the block.

PHPBB3-11241
[ticket/11241] Fix the dropdown in RTL languages.

PHPBB3-11241
[ticket/11241] Add events & var for extensions to dropdown.

PHPBB3-11241
[ticket/11241] Add border to dropdown menu options.

PHPBB3-11241