Bug Fix - #312 Changing one task changes another

- Added a warning when modifying recurring tasks, that all instances of
  that task may be modified.  When task confirms a bulk edit the
  recurrence is again indicated (thanks to Cory Donnelly).

src/command.cpp

@@ -958,6 +958,13 @@ int handleModify (std::string &outs)
            task->get ("parent") == other->get ("parent")) || // Sibling
           other->get ("uuid")   == task->get ("parent"))     // Parent
       {
+        if (task->has ("parent"))
+          std::cout << "Task "
+                    << task->id
+                    << " is a recurring task, and all other instances of this"
+                    << " task may be modified."
+                    << std::endl;
+
         Task before (*other);
 
         // A non-zero value forces a file write.