(svn r9849) [0.5] -Backport from trunk (r9693, r9694, r9697, r9718, r9719, r9725 and 9726):

- Fix: Crash when destroying bridge with train partially on it [FS#738] (r9726)
- Fix: Planes made a 270 degree turn instead of a 90 degree turn on the southern runway of the intercontinental airport [FS#743] (r9725)
- Fix: In-game private messages did not work for clients with high ClientIDs (r9719)
- Fix: Do not allow building of rail vehicles whose railtype is not available (r9718)
- Fix: [YAPF] The guessed path was ignored for ships [FS#736] (r9694)

engine.c

@@ -414,6 +414,12 @@ bool IsEngineBuildable(EngineID engine, byte type, PlayerID player)
 	// check if it's available
 	if (!HASBIT(e->player_avail, player)) return false;
 
+	if (type == VEH_Train) {
+		/* Check if the rail type is available to this player */
+		const Player *p = GetPlayer(player);
+		if (!HASBIT(p->avail_railtypes, EngInfo(engine)->railtype)) return false;
+	}
+
 	return true;
 }