Added better backwards compatibility by reducing the minimum api version to 1.13, and lowering the java build target to 1.8. It is still strongly recommended to use the latest version of Minecraft and Java, as those are what I work and test with.
The world and coordinates of a killed dragon can now be included in the kill reward commands. These can either be in a Spigot or Vanilla format, default as Vanilla so they can be used in execute commands.