Fix lever script and convert rest to meta

Solves #1278
Replace L30-33 with this
```Lua
local stone
for i = 1, #stones do
	stone = Tile(stones[i]):getItemById(1304)
	if stone then
		stone:remove()
		stones[i]:sendMagicEffect(CONST_ME_EXPLOSIONAREA)
	end
end
```