[ticket/12005] Remove PM popup setting from user preferences
PHPBB3-12005
[ticket/12005] Remove PM popup from converter
PHPBB3-12005
[ticket/12005] Remove PM popup UCP module
PHPBB3-12005
[ticket/12005] Remove PM popup
PHPBB3-12005
[ticket/12005] Remove language vars used by PM popup
PHPBB3-12005
[ticket/12005] Delete templates files
PHPBB3-12005
[ticket/12005] Remove PM popup module from DB
PHPBB3-12005
Merge pull request #1854 from Pico88/ticket/12005

[ticket/12005] Remove code responsible for PM popup completely