Fix for cheeseblock crash

I did a little bit of searching through the code and found the problem for the cheeseblock crash. When the cheeseBlock-Item is "created" in GCItems.initItems(); it references the cheeseBlock-Block before it was created, causing a NullPointerException later. Switching these two lines solve the problem. I'm not entirely sure if this will break anything else though... I created this pull request so I could share my findings on the problem. This should fix #615

Forgive me if this pull request is a bad idea. I'm just trying to share my thoughts.