[New Feature] Enable more high bridges

[CatTanker]

If Possible, increase the number of possible bridges
Especially for mods which use trains, there is ideally 5-6+ bridges which would be needed
For mods with significant details more would be needed for different road types and so on...

As far as I'm aware there's a limit to 4 bridge types currently.
Map editor changes would also be required for this.