acquisition: drive a DataSource from the registry; --source and --source-opt

src/source_dialog.cpp

@@ -1129,10 +1129,10 @@ gboolean pick_probe(gpointer user) {
 }  // namespace
 
 void apply_stored_settings(Config& cfg) {
-  const std::string want = active_configuration(cfg.server, cfg.port);
+  const std::string want = active_configuration(cfg.session_host(), cfg.session_port());
   if (want.empty()) return;
   LayoutState st;
-  if (!load_layout(configuration_path(cfg.server, cfg.port, want), st)) return;
+  if (!load_layout(configuration_path(cfg.session_host(), cfg.session_port(), want), st)) return;
   // Only where nothing newer was said: a flag the user typed, or the preferences they just applied,
   // wins -- because it is the more recent statement of intent, and the file is not a place to hide a
   // surprise from whoever just made it.