a0.21 is a bugfix update with no changes to the API

- This update improves the initial loading of plugins. The loader will no longer attempt to load every single jar file in your plugins folder. Instead it will first try to recognize it as a Haxe plugin and load it when it has detected it as one.
Some plugins would cause the loader to crash because it tried to load the plugin. This bug was reported to me on Discord, feel free to report bugs!

- To help developers, the loader now gives a warning when a supposed Haxe plugin does not implement the Gate interface.

- Events that should get cancelled are now cancelled before the "occurrence" logic is called.

- The PlayerMoveEvent now runs synchronously by default and it won't log to the console when it's called, both to improve performance.

- The 'new update available' message is now just yellow and does not use underline.