fixed misplacing a Grill deletes it from the inventory.

If the player tries to place a Grill where it is not allowed, the Grill block is not added to the world
but the item is deleted from the players inventory (some conditions).
I also moved the first checkSides to the inner 'if' since it is not relevant for the second 'if'.

Fix for http://terrafirmacraft.com/f/topic/7078-grill-deletion-bug-re-fueling-confusion/#entry94893
but I also came across this last night when trying to figure out how to use a Grill...

Something to think about: should the conditions to place a Grill also be
checked after it was placed, that is, should the Grill be dropped if one
of the blocks needed to place it is removed?