loadChunk returns a workspace

Code/Mantid/Framework/API/inc/MantidAPI/DataProcessorAlgorithm.h

@@ -57,8 +57,8 @@ protected:
   void setPropManagerPropName(const std::string &propName);
   void mapPropertyName(const std::string &nameInProp, const std::string &nameInPropManager);
   void copyProperty(API::Algorithm_sptr alg, const std::string& name);
-  ITableWorkspace_sptr determineChunk(const std::string &filename);
-  void loadChunk(const size_t rowIndex);
+  virtual ITableWorkspace_sptr determineChunk(const std::string &filename);
+  virtual MatrixWorkspace_sptr loadChunk(const size_t rowIndex);
   Workspace_sptr load(const std::string &inputData,
                       const bool loadQuiet = false);
   std::vector<std::string> splitInput(const std::string &input);

Code/Mantid/Framework/API/src/DataProcessorAlgorithm.cpp

@@ -189,7 +189,7 @@ ITableWorkspace_sptr DataProcessorAlgorithm::determineChunk(const std::string &f
       "DataProcessorAlgorithm::determineChunk is not implemented");
 }
 
-void DataProcessorAlgorithm::loadChunk(const size_t rowIndex) {
+MatrixWorkspace_sptr DataProcessorAlgorithm::loadChunk(const size_t rowIndex) {
   UNUSED_ARG(rowIndex);
 
   throw std::runtime_error(