add tokenizer

```javascript
var mml = "t120 l{{len}} cdef @hello(10, 20) gab<c >";

var tokens = Wamml.tokenize(mml);
/*
[
  { type: "char"      , value: "t"   },
  { type: "number"    , value: "120" },
  { type: "char"      , value: "l"   },
  { type: "punctuator", value: "{{"  },
  { type: "char"      , value: "l"   },
  { type: "char"      , value: "e"   },
  { type: "char"      , value: "n"   },
  { type: "punctuator", value: "}}"  },
  { type: "char"      , value: "c"   },
  { type: "char"      , value: "d"   },
  { type: "char"      , value: "e"   },
  { type: "char"      , value: "f"   },
  { type: "punctuator", value: "@"   },
  { type: "char"      , value: "h"   },
  { type: "char"      , value: "e"   },
  { type: "char"      , value: "l"   },
  { type: "char"      , value: "l"   },
  { type: "char"      , value: "o"   },
  { type: "punctuator", value: "("   },
  { type: "number"    , value: "10"  },
  { type: "punctuator", value: ","   },
  { type: "number"    , value: "20"  },
  { type: "punctuator", value: ")"   },
  { type: "char"      , value: "g"   },
  { type: "char"      , value: "a"   },
  { type: "char"      , value: "b"   },
  { type: "punctuator", value: "<"   },
  { type: "char"      , value: "c"   },
  { type: "punctuator", value: ">"   }
]
*/