Fixed Downloader class progress callbacks, added HTTP::Parser progress calculation function.

lib/http_parser.cpp

@@ -751,6 +751,13 @@ bool HTTP::Parser::Read(std::string &strbuf){
   return parse(strbuf);
 }// HTTPReader::Read
 
+/// Checks download completion percentage.
+/// Returns zero if that doesn't make sense at the time or cannot be determined.
+uint8_t HTTP::Parser::getPercentage() const{
+  if (!seenHeaders || length < 1){return 0;}
+  return ((body.length() * 100) / length);
+}
+
 /// Attempt to read a whole HTTP response or request from a data buffer.
 /// If succesful, fills its own fields with the proper data and removes the response/request
 /// from the data buffer.