* Multipart form content length calculation

* HTMLForm test

Net/src/PartSource.cpp

@@ -41,6 +41,9 @@ namespace Poco {
 namespace Net {
 
 
+const int         PartSource::UNKNOWN_CONTENT_LENGTH     = -1;
+
+
 PartSource::PartSource():
 	_mediaType("application/octet-stream")
 {
@@ -69,5 +72,9 @@ const std::string& PartSource::filename() const
 	return EMPTY;
 }
 
+std::streamsize PartSource::getContentLength() const
+{
+	return UNKNOWN_CONTENT_LENGTH;
+}
 
 } } // namespace Poco::Net