A superclass for the the Multiple File Upload user control. Responsible for recieving information about current media folder node, user context id and node id path from the Multiple File Upload IDataTypeEditor. A custom Multiple File Upload user control must inherit this class inorder to be instatiated by the Multiple File Upload IDataTypeEditor. The information must be passed on as querystrings to the MultipleFileUploadHandler. Use the FullMultipleFileUploadHandlerURL getter to get the full URL inclusive required querystring variables.