[ticket/10948] Separate color swatch cells.

PHPBB3-10948
Merge remote-tracking branch 'prototech/ticket/10948' into develop

* prototech/ticket/10948:
  [ticket/10948] Separate color swatch cells.
[ticket/11672] Removed unnecessary text from alerts.

Messages like "Return to forum last visited" are entirely unnecessary
when using AJAX to delete a post, so this commit removes them.

PHPBB3-11672
[ticket/11672] Replace sprintf() usage with $user->lang().

PHPBB3-11672
[ticket/11672] Remove some messages that were missed in mcp_queue.php.

PHPBB3-11672