imgui user interface implementation

Classes.h

@@ -33,6 +33,7 @@ class scenario_time;
 class TMoverParameters;
 class ui_layer;
 class editor_ui;
+class itemproperties_panel;
 class event_manager;
 class memory_table;
 class powergridsource_table;
@@ -42,6 +43,7 @@ struct light_array;
 
 namespace scene {
 struct node_data;
+class basic_node;
 }
 
 namespace Mtable