Flat Top Barge 1.1

• Added transverse thrusters to move sideways. Useful to keep the barge against a dock.
• Added JATO option. Adust the thrust in the tuning menu.
• Changed Xbox controls, A/X for main thrust, LB/RB for transverse thrust, dpad down for JATO.
• Added "army" and "spacex" skins (as requested)
• Added couplers on the front and back to enable multiple barges to be linked.