Make it possible to add efficiency to brushes

The idea is basically that you could add efficiency to the brush, but for each level of efficiency there is an increased percentage chance that the item inside would "break" like we say in the original archaeology trailer. This allows you to choose whether you want the trade-off of potentially losing the item you're excavating so that you can brush faster. It also adds to the realism of archaeology as you have to be careful and patient to make sure you don't damage the artefacts. Yeah, you could pull a Heinrich Schliemann and go fast but you're likely to destroy history