Made torpedos not travel through land, but destroy bridges

as this is legacy RA95 behavior I would like to see here for consistency and balancing reasons. #2097 Allies have many ways to destroy long bridges with ships. I cleaned up the hard-coded target code (Water == Water, Ground == !Water)  which gets rid of unwanted inconsistencies like flak truck and rocket troopers being unable to target water and bridges just because they defined `ValidTargets: Air, Ground` although no `InvalidTargets` were set and torpedos travelling through land when the target was missed #3252 which was not catched by just making the target cursor invalid.