Merge branch 'master' into jgrpp

# Conflicts:
#	src/airport_gui.cpp
#	src/build_vehicle_gui.cpp
#	src/direction_type.h
#	src/gfx_type.h
#	src/group_gui.cpp
#	src/misc_gui.cpp
#	src/rail_gui.cpp
#	src/road_gui.cpp
#	src/signs_gui.cpp
#	src/slope_func.h
#	src/smallmap_gui.cpp
#	src/terraform_gui.cpp
#	src/toolbar_gui.cpp
#	src/town_gui.cpp
#	src/town_type.h
#	src/vehicle_type.h
#	src/widget_type.h

src/company_type.h

@@ -35,6 +35,7 @@ enum Owner : byte {
 	COMPANY_SPECTATOR       = 255, ///< The client is spectating
 };
 DECLARE_POSTFIX_INCREMENT(Owner)
+DECLARE_ENUM_AS_ADDABLE(Owner)
 
 static const uint MAX_LENGTH_PRESIDENT_NAME_CHARS = 32; ///< The maximum length of a president name in characters including '\0'
 static const uint MAX_LENGTH_COMPANY_NAME_CHARS   = 32; ///< The maximum length of a company name in characters including '\0'