Throwable Weapons etc

Added copper spear, made axes act like the weapons, added reinforced
shield (4 bronze ingots in cross around a wooden shield), fixed some
bugs, added stone, copper, and bronze javelins. The javelins stack to 4.
You can use them in the same way as the weapons, but if you press and
hold the drop item key (q by default) then you throw them with a
variable strength. They have a chance to break on impact equal to
1/maxDamage. This means that more damaging weapons break less
frequently. It ain't perfect, I know, but if you mess with the item
damage then they no longer stack. Unfortunately there's no feedback on
you charging up a throw. You just have to get used to how long you need
to hold down the key.