Continous level crossing closed (warning) sound as patch

[kyosuke1989]

Currently, level crossings don't make any warning sound when closed by PBS signal from far away, they only do have an sound played when train is already passing the crossing (remains from old time before PBS signals were implemented, and train closed a crossing just before passing it = behaviour was ok, since sound was played straight after crossing was closed)

Could it be made to patch parameter to have a possibility to choose level crossing sound effect from different behaviours:

- Off (some people would like this option as well)
- When a train is on crossing <- Current behaviour, and would be default behaviour on patch setting, so no-one could be annoyed of this too much
- Continous when crossing is closed (new selectable sound effect behaviour)

On the other hand, how hard it would be to code to have a continous level crossing alarming sound option for NewGRF's ? So NewGRF authors could use them as option if wanted.

I would have four options on mind which could be used on NewGRF railtype-definable level crossings (and these options would be (selected) coded on railtypes using NML):

- No sound at all (for unguarded railtype-definable crossings, which DO play alarming sound at the moment )
- When train closes the crossing (just momentary sound, for urban guarded level crossings and old mech. barriers)
- Continous when crossing is closed, but terminated when train reaches the crossing (this behaviour is used at many guarded level crossings)
- Continous when crossing is closed (this behaviour is used at many guarded level crossings)