Add function references

common.lua

@@ -0,0 +1,22 @@
+local common
+common = {
+	--- recursively copy a table, handle cyclic references, no metatable
+	copy = function(t, cache)
+		if type(t) == "table" then
+			cache = cache or {}
+			if cache[t] then
+				return cache[t]
+			else
+				local c = {}
+				cache[t] = c
+				for k, v in pairs(t) do
+					c[k] = common.copy(v, cache)
+				end
+				return c
+			end
+		else
+			return t
+		end
+	end
+}
+return common