Multiplayer fixes:
* hellworld=true no longer overwrites old save chunks. Player positions will still break if you switch it on a running server, though
* boats are now visible to other players
* minecarts move nicer
* fishing kinda sorta works, but needs more work
* sheep and cows look like sheep and cows now
* buckets work now
* fixed stairs being really difficult to destroy
* increased the timeout before “Took too long to log in”
* made it possible to ride carts and boats (pigs should work too..)