Fixes and more stuff

-Fixed weedkiller grenade not working
-Reduced the size of which backpacks can hold items
-Riot shield has a chance to block and weaken a pouncing alien
-Shotgun pumping sound fixed
-Added flares to vending machines
-Reduced the amount of donuts in vendors
-Fixed knife icon being in the wrong hand
-M41a can now be placed on back
-Updated MOTD
-Fixed alien health hud not shown property
-Buffed combat knife damage
-Buffed colt damage
-Nerfed stun prod stun time, but added one more charge
-Added loading shell sound (untested)