Optional world name in `/tardistravel [world-name] [x y z]`

[eccentricdevotion]

Transferred from Bukkit Dev 1275 user_10479419 created this issue Apr 26, 2016

Currently when you want to travel to specific coordinates, you need to also specify the world's name.

I propose to make the world's name optional, so when you only type coordinates, it travels to the current world.