The new tool will say whether a target block type is present in a
specified region, to allow for more targeted digging. It is deliberately
quite weak, with several limitations: only stores enough charge for a
small number of shots; target can only be set by pointing at an example
node; range is limited; accuracy is less than 100%. Some of these
limitations should probably be ameliorated, but not entirely eliminated,
in the future when we have a better idea of game balance.
The inventory image is only a placeholder.
