The Download group of packets was in desperate need for a restructuring.
Now, instead of using `DownloadServerList` to list everything, different object types now are downloaded through their own seperate packets. (Improving network efficiency)
Spigot 1.13 has a compatabilty layer for old bukkit names, this will allow you to take advantage of that.
1.12: `bukkit:grass` -> `minecraft:grass`
1.13: `bukkit:grass` -> `minecraft:grass_block`
1.13: `grass` -> `minecraft:grass`
This is how SubServers will implement the Validator API that I suggested. I had to make some assumptions though (like how I don't expect BungeeCord's api to have a setTabValidator() method).
This marks the beginning of SubServers.Host. As of now it is just a
simple plugin loading API, but it is planned to become a way to host
servers on other machines.
Also, SubAPI now checks to make sure variables aren't null in many
places.
