Add TODO list.

TODO

@@ -0,0 +1,15 @@
+TODO list for typehinting branch.
+Below list contains things that should be changed/fixed/implemented.
+
+
+1. mixed[] $arr = array(5, '5');
+	var_dump shows some trash information about $arr variable.
+
+2. int[] $arr = {5, 5};
+	This syntax is unsupported yet. Should replace the array() function.
+
+3. Data types like char or void are still not supported.
+
+4. Class properties do not support strict data type hinting.
+
+5. Closures and methods declaration / definition uses function keyword.