Skipper sign
This sign will, when crossed, tell the minecart or train to skip certain upcoming signs. Useful for making trains ignore a particular station or as a sign activation filter.

Slowdown modes
Slowdown changed from a simple boolean to allow for specifying what kind of slowdown is enabled or disabled. This introduces two new commands:

• /train slowdown gravity [true/false] - turn gravity-based slowdown/speedup on or off
• /train slowdown friction [true/false] - turn friction speed reduction over time on or off

Likewise these can be set on property signs:
In default train properties/properties YAML, these are saved as a node replacing the old true/false.
The old true/false slowdown properties still function and set all (both) modes on or off simultaneously.

Fixes:

• Slowdown false works properly on vertical rails
• Vertical rails have the same gravity-based slowdown as sloped rails. To change it back to the broken old values, set legacyVerticalGravity to true in the config.yml
• Fix a potential invalid block collision when taking a curve down a slope
• Minecarts are now edited automatically when placed on non-standard rails (vertical rails, pressure plates, etc.)
• Tickets # uses not updating when entering a train