Revert changes to Load that have broken the LoadTest system test

This reverts the changes to Load from commits
  - 67348e40
  - cf334a95

We need a better way for a specific loader to request that it will handle
all files that Load has found.
Refs #10061

Code/Mantid/Framework/DataHandling/inc/MantidDataHandling/Load.h

@@ -101,8 +101,6 @@ namespace Mantid
       API::IAlgorithm_sptr m_loader;
       /// The name of the property that will be passed the property from our Filename
       std::string m_filenamePropName;
-      /// Indicate whether a collection of files should be loaded into a single workspace.
-      bool m_loadMultipleAsOne;
       /// Mutex for temporary fix for #5963
       static Poco::Mutex m_mutex;
     };

Code/Mantid/Framework/DataHandling/src/Load.cpp

@@ -170,24 +170,12 @@ namespace Mantid
             // ... store it's name and version and check that all other files have loaders with the same name and version.
             std::string name = loader->name();
             int version = loader->version();
-            std::string ext = fileNames[0].substr(fileNames[0].find_last_of("."));
             for(size_t i = 1; i < fileNames.size(); ++i)
             {
-              // If it's loading into a single file, perform a cursory check on file extensions only.
-              if(dynamic_cast<MultipleFileProperty*>(loader->getPointerToProperty("Filename")) != NULL)
-              {
-                if( fileNames[i].substr(fileNames[i].find_last_of(".")) != ext)
-                {
-                  throw std::runtime_error("Cannot load multiple files when more than one Loader is needed.");   
-                }
-              }
-              else
-              {
-                loader = getFileLoader(fileNames[i]);
-
-                if( name != loader->name() || version != loader->version() )
-                  throw std::runtime_error("Cannot load multiple files when more than one Loader is needed.");        
-              }
+              loader = getFileLoader(fileNames[i]);
+
+              if( name != loader->name() || version != loader->version() )
+                throw std::runtime_error("Cannot load multiple files when more than one Loader is needed.");
             }
           }
 
@@ -237,18 +225,11 @@ namespace Mantid
       const auto & props = loader->getProperties();
       for(auto it = props.begin(); it != props.end(); ++it)
       {
-        auto *fp = dynamic_cast<API::MultipleFileProperty*>(*it); 
-        auto *fp2 = dynamic_cast<API::FileProperty*>(*it);
-        if(fp)
+        if(auto *fp = dynamic_cast<API::FileProperty*>(*it))
         {
           m_filenamePropName = fp->name();
           break;
         }
-        if(fp2)
-        {
-          m_filenamePropName = fp2->name();
-          break;
-        }
       }
       if(m_filenamePropName.empty())
       {
@@ -315,7 +296,6 @@ namespace Mantid
       exts.push_back(".h5");
       exts.push_back(".hd5");
       exts.push_back(".sqw");
-      exts.push_back(".fits");
 
       declareProperty(new MultipleFileProperty("Filename", exts),
         "The name of the file(s) to read, including the full or relative "
@@ -343,15 +323,11 @@ namespace Mantid
      * Executes the algorithm.
      */
     void Load::exec()
-    { 	
+    {
       std::vector<std::vector<std::string> > fileNames = getProperty("Filename");
       
-      // Test for loading as a single file      
-      IAlgorithm_sptr loader = getFileLoader(fileNames[0][0]);
-      m_loadMultipleAsOne = dynamic_cast<MultipleFileProperty*>(loader->getPointerToProperty("Filename")) != NULL;
-
-      if(isSingleFile(fileNames) || m_loadMultipleAsOne)
-      {        
+      if(isSingleFile(fileNames))
+      {
         // This is essentially just the same code that was called before multiple files were supported.
         loadSingleFile();
       }
@@ -363,7 +339,7 @@ namespace Mantid
     }
 
     void Load::loadSingleFile()
-    {      
+    {
       std::string loaderName = getPropertyValue("LoaderName");
       if( loaderName.empty() )
       {