Add roadstop GRF properties to set bridge heights and disallowed pillars

src/newgrf_extension.h

@@ -50,6 +50,8 @@ enum Action0RemapPropertyIds {
 	A0RPI_ROADSTOP_ANIMATION_TRIGGERS,
 	A0RPI_ROADSTOP_CALLBACK_MASK,
 	A0RPI_ROADSTOP_GENERAL_FLAGS,
+	A0RPI_ROADSTOP_MIN_BRIDGE_HEIGHT,
+	A0RPI_ROADSTOP_DISALLOWED_BRIDGE_PILLARS,
 };