Makes a rectangular hole in semi-solid materials. The return value is the amount of pixels that were dug free. If no_dig2objects is true, the dug out material does neither create objects according to the Dig2Objects in the
*.ocm nor will the amount be stored in the internal buffer.
CreateShaft im Fahrstuhl gräbt einen Fahrstuhlschacht.
DigFreeRect(700, 1500, 15, 15);
Gräbt ein kleines quadratisches Loch mitten in die Landschaft.