Enhancement - history report

- Implemented history report.
- Improved (not to the point of them working) filters.
- Improved automatic filter construction.
- Removed obsolete members from Task.
- Added tag support to the "add" command.

src/command.cpp

@@ -73,6 +73,10 @@ std::string handleAdd ()
       context.task.set ("priority", defaultPriority);
   }
 
+  // Include tags.
+  foreach (tag, context.tagAdditions)
+    context.task.addTag (*tag);
+
   // Only valid tasks can be added.
   context.task.validate ();