make Parser::Parse accept istreams instead of stringstream

AUTHORS

@@ -7,4 +7,4 @@ a license to everyone to use it as detailed in LICENSE.)
 M. Petra Baranski (info@progsource.de)
 Patrick José Pereira (patrickelectric@gmail.com)
 Martin Kopecky (martin.kopecky357@gmail.com)
-
+Evan Klitzke (evan@eklitzke.org)