Add simple item fluid storage API

tools/jetpack.lua

@@ -96,10 +96,11 @@ local function onGlobalStep(player,inv,itemstack,index,def)
 end
 
 jetpack.tryFly=function(itemstack)
-	if itemstack:get_wear()>=65533 then
+	local meta=itemstack:get_meta()
+	if meta:get_int("industrialtest.fluidAmount")==0 then
 		return false
 	end
-	itemstack:set_wear(itemstack:get_wear()+2)
+	industrialtest.api.addFluidToItem(itemstack,-1)
 	return true
 end
 
@@ -109,9 +110,12 @@ registerJetpack({
 	displayName=S("Jetpack"),
 	groups={
 		_industrialtest_fueled=1,
-		_industrialtest_emptyOnConstruct=1
+		_industrialtest_fluidStorage=1
 	},
-	tryFly=jetpack.tryFly
+	tryFly=jetpack.tryFly,
+	customKeys={
+		_industrialtest_fluidCapacity=5000
+	}
 })
 minetest.register_craft({
 	type="shaped",