Players who are riding something are now (unfortunately) ejected when knocked back from the border. This was necessary due to the Bukkit team removing the ability to teleport entities which have a passenger or are the passenger of another entity.

Note that I tried to work around it by ejecting the player, teleporting the entity they were riding (minecart, pig, whatever), and then setting the player as passenger again, but it was bugged and only halfway treating the player as if they were riding something.
riding something across the border would double-trigger the border crossing handler since leaving a vehicle fires a teleport event (go figure); fixed

Players going through a portal will now no longer be able to generate chunks outside the border; the portal teleport location is re-targeted inside the border to prevent that so that new portals aren't created outside the border

added redstone comparator and activator rail to "safe open blocks" list for knockback safe location finder