(svn r8301) -Codechange: Move the code relating to the sign list window from graph_gui.cpp to a file of its own: signs_gui.cpp.

source.list

@@ -208,6 +208,7 @@ road_gui.cpp
 roadveh_gui.cpp
 settings_gui.cpp
 ship_gui.cpp
+signs_gui.cpp
 smallmap_gui.cpp
 station_gui.cpp
 subsidy_gui.cpp