add types and inverting operators (version 0.0.6)

examples:
 $a = ~5; // -6
 $a = (string)5; // '5'
 $a = (int)5.5; // 5

Change-Id: Id8980a6e1d2a82813dd4fbbe03f25f74fb42076e
Merge "add types and inverting operators (version 0.0.6)"