update Resource according to Gui implementation

engine/resource/Resource.h

@@ -45,6 +45,7 @@ const char* const CONFIG_EXTENSION			= "config";
 const char* const PACKAGE_EXTENSION			= "package";
 const char* const UNIT_EXTENSION			= "unit";
 const char* const PHYSICS_EXTENSION			= "physics";
+const char* const GUI_EXTENSION				= "gui";
 
 const uint32_t TEXTURE_TYPE					= 0x0DEED4F7;
 const uint32_t MESH_TYPE					= 0x742FBC9A;
@@ -57,6 +58,7 @@ const uint32_t CONFIG_TYPE					= 0x17DEA5E1;
 const uint32_t PACKAGE_TYPE					= 0xC0A2212C;
 const uint32_t UNIT_TYPE					= 0x516224CF;
 const uint32_t PHYSICS_TYPE					= 0xFA32C012;
+const uint32_t GUI_TYPE						= 0x2C56149A;
 
 /// ResourceId uniquely identifies a resource by its name and type.
 /// In order to speed up the lookup by the manager, it also keeps