Display total aggregated loss curves

[ptormene]

With a complete event-based risk calculation, all tags and realizations can be chosen correctly to show the aggregated curve by realization and/or tag. However, the total aggregated curves, available in the agg_curves.csv output, are not available in the drop down menu (no * option like in other drop down menus of the plugin). Without it, the user cannot see the total aggregated curve for the whole building inventory, nor make comparisons among the aggregated curves by tags.
As soon as the engine provides this functionality, we may leverage it with the plugin.