Running into a wall with multiple passengers #TrainsInMotion #Traincraft (1.7 rewrite)

- fixed some crash on start errors with servers.
- Fixed a server crash related to null bogies.
- Moved passenger sync to generic rail transport so we can use it with trains too.
- Reworked some NBT variable stuff, now it should be more efficient.
- Added a new permissions checker that should make things easier to manage in the future.


At this point multiple passengers should work, and it has almost all the functionality that 1.10 does for it, but this refuses to work. This will likely take more time than anticipated to get working. The best case scenario it seems that the player knows it's on the train, and the train knows the player is in the list of riders, but the train won't move the entity to the proper position.

One other idea I have (courtesy of ZnD) is to make a list of entities similar to the bogies and just keep them moving with the thing, but that's gonna be nasty in almost every way.
If there's no other way I guess I have no choice but I'd like to find a better method.