Added the carbine to the game

-Costs 300
-Damage is twice that of rifle
-Fire rate is 150 (just less than half that of rifle)
-Clip size is 40
-For a new sound, stick https://soundcloud.com/forty-bot/carbine-fire-sound in main/models/weapons/carbine/ as flash0.wav; no firing sound otherwise

-Change machinegun to submachine gun