weird power coupling physics thing

[melkfles]

found a bug where if a block is connected via a power coupling and a detachable block, when you activate the detachable block the block would still be connected. even with the power coupling strenght on 0, the block should fall but it still stays connected to the main body . (tried to make something among the lines of a TOW missile)

[alvaroping1]

known. You need to detach a weld grou