New optimisation options + network improvements +

Added optimisation options (use more ram less CPU)
Added new delay system for Loco syncing (smooths out train movement for clients)
Made diesel engine sound deactivate when out of fuel
Smokestack heat affect now only shows if fire is strong enough to boil water.
Lowered memory use+performace of many textures
Added missing links for side tank trains/tenders (would break the game if bought)