[ticket/13052] Remove additional parameter from check_form_key()

PHPBB3-13052
[ticket/13052] Fix appearances with multiple parameters

PHPBB3-13052
[ticket/13052] Use request class instead of $_POST and request_var()

PHPBB3-13052
Merge pull request #2935 from nickvergessen/ticket/13052

Ticket/13052 Remove additional parameter from check_form_key()

* nickvergessen/ticket/13052:
  [ticket/13052] Use request class instead of $_POST and request_var()
  [ticket/13052] Fix appearances with multiple parameters
  [ticket/13052] Remove additional parameter from check_form_key()