feedback: Replace taskDiff method by Task inequality operator

src/commands/CmdDenotate.cpp

@@ -124,7 +124,7 @@ int CmdDenotate::execute (std::string& output)
       }
     }
 
-    if (taskDiff (before, task))
+    if (before != task)
     {
       std::string question = format (STRING_CMD_DENO_CONFIRM,
                                      task.id,

src/commands/CmdImport.cpp

@@ -184,10 +184,10 @@ void CmdImport::importSingleTask (json::object* obj)
   {
     // "modified:" is automatically set to the current time when a task is
     // changed.  If the imported task has a modification timestamp we need
-    // to ignore it in taskDiff() in order to check for meaningful
+    // to ignore it in task comparison in order to check for meaningful
     // differences.  Setting it to the previous value achieves just that.
     task.set ("modified", before.get ("modified"));
-    if (taskDiff (before, task))
+    if (before != task)
     {
       CmdModify modHelper;
       modHelper.checkConsistency (before, task);

src/commands/CmdModify.cpp

@@ -76,7 +76,7 @@ int CmdModify::execute (std::string& output)
     Task before (task);
     task.modify (Task::modReplace);
 
-    if (taskDiff (before, task))
+    if (before != task)
     {
       // Abort if change introduces inconsistencies.
       checkConsistency(before, task);