Priority values are inherited now.

However, they would be better inherited only during sorting, as otherwise they show up in the UI and possibly get recorded in the userlist using their inherited values. Part of #165 work.

src/backend/graph.cpp

@@ -209,6 +209,8 @@ namespace loot {
 
             //parentPriority is now the highest priority value of any plugin that the current plugin needs to load after.
             //Set the current plugin's priority to parentPlugin.
+            if (graph[*vit].Priority() < parentPriority)
+                graph[*vit].Priority(parentPriority);
 
         }
     }