WorldEditListener Rewrite (Only onPlayerCommandPreprocess)

I've removed all other event checks which I found to be unnecessary (e.g. player move event). Basically, it checks first if it is a generation command e.g. //sphere then it will check if you are in the plot and you have permission and will set the mask accordingly. If it is another WorldEdit command e.g. //set then it sets the mask but first checks that the two locations of the cuboid selection are within the same plot and the player has permission.