moved inventory menu definition of chest and furnace to content_nodemeta.{h,cpp}

src/main.cpp

@@ -335,6 +335,9 @@ Misc. stuff:
 - Finish the ActiveBlockModifier stuff and use it for something
 - Move mineral to param2, increment map serialization version, add conversion
 
+TODO: Create a common interface-whatever-thing to implement custom
+      special blocks with an inventory menu
+
 Making it more portable:
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