Un-check "Leave shadow topic in place" checkbox when moving topics

As per Raimon's suggestion..

In all my styles I make sure that on line 16 of mcp_move.html, "checked="checked"" is deleted so that a shadow topic is not made every single time a topic is moved (without having to uncheck it everytime otherwise). I believe it makes a mess especially if you move all your spam messages into a private forum instead of deleting them. I do not believe that it is a feature that should be on by default.