core: set config defaults a second time before loading

Works around an issue where media cache directories would be set before the
app name is set (which Qt uses to return the local appdata dirs used to
set the cache directories).

app/core.cpp

@@ -116,6 +116,10 @@ void Core::Start()
   // Set up the index manager for renderers
   IndexManager::CreateInstance();
 
+  // Reset config (Config sets to default on construction already, but we do it again here as a workaround that fixes
+  //               the fact that some of the config paths set by default rely on the app name having been set (in main())
+  Config::Current().SetDefaults();
+
   // Load application config
   Config::Load();