Update to v4 of house placing patch.

src/settings_type.h

@@ -487,6 +487,7 @@ struct EconomySettings {
 	bool   station_noise_level;              ///< build new airports when the town noise level is still within accepted limits
 	uint16 town_noise_population[3];         ///< population to base decision on noise evaluation (@see town_council_tolerance)
 	bool   allow_town_level_crossings;       ///< towns are allowed to build level crossings
+	bool   allow_placing_houses;             ///< whether to allow placing houses manually also during gameplay, not only in scenario editor
 	bool   infrastructure_maintenance;       ///< enable monthly maintenance fee for owner infrastructure
 };