Fix issue pointed out by Supereg; store dimension on first join too (#1979) * Only double switch if the dimension is the same. According to the protocol, a double respawn packet is only needed to be dimension, This also maintains the same behaviour for Spigot https://hub.spigotmc.org/stash/projects/SPIGOT/repos/craftbukkit/commits/ad2f806097e51fbf72f64ba97e2e4c3785326f42
* Store current dimension on first disconnect too (commit: 18f57f2)
