I considered renaming sendDataPacket() to dataPacket() to reduce the BC breaks, but the parameter set has changed, which might cause astonishing behaviour, so it's better to break it in a loud way. Also, this has a clearer name.
This supports vanilla placement of paintings, with overlap and collision checking.
Paintings are removed when a block is placed inside them or if any of their supporting blocks are removed.
As per vanilla, a random painting is chosen from the largest subset that will fit into the given space.
