Add utils lib with read_ui16 function

Signed-off-by: Ryan Harvey <ryan.b.harvey@gmail.com>

utils.lua

@@ -0,0 +1,13 @@
+local function read_ui16(byte1, byte2)
+    assert (0 <= byte1 and byte1 <= 0xff)
+    assert (0 <= byte2 and byte2 <= 0xff)
+    local res  = bit.bor(
+        bit.lshift(byte1, 8),
+        bit.lshift(byte2, 0)
+    )
+    return res
+end
+
+return {
+    read_ui16 = read_ui16
+}