Various fixes/changes

- Return false for isAirBlock in TankAirBlock(fixes ability to replace
the blocks with lava/water)
- Changed tankAir material from Material.air to Material.leaves(fixes
ability to replace the blocks with lava/water)
- Clean up imports in TankLayerScan removing the import for
scala.compat.Platform$ (fixes crash when there is no scala library)
- Add wooden armor recipes