Small Bugfix Update

Restarting a level no longer crashes the game (doh). - The final boss of the first mission now actually comes back if it charges off the screen. - Parts of bosses should no longer suddenly hit warp speed when the main boss is destroyed. - Slightly less flickering on the effects for the shard cannon and ricoshard weapons. - The Cargo Ship with special weapon upgrades is now rate-limited so you won't constantly get them spawning towards the ends of missions. - Some more performance improvements around certain weapons.