switch html5lib to new pkg layout

lib/src/encoding_parser.dart

 #library('encoding_parser');
 
 #import('constants.dart');
 #import('inputstream.dart');
 #import('utils.dart');
 
 // TODO(jmesserly): I converted StopIteration to NoMoreElementsException. Seems
 // strange to throw this from outside of an iterator though.
 /**
  * String-like object with an associated position and various extra methods
@@ skipping 363 matching lines @@
     }
   }
 }
 
 
 bool isSpaceOrAngleBracket(String char) {
   return char == ">" || char == "<" || isWhitespace(char);
 }
 
 typedef bool CharPreciate(String char);