add lua example

tests/script/sh/scalar_demo.lua

+funcName = "test"
+
+ans = 1 
+
+function test_init()
+  return ans  
+end
+
+function test_add(rows, ans)
+  for i=1, #rows do
+    rows[i] = rows[i] + ans  
+  end
+  return rows 
+end