Adds support for using the same command executor for multiple command sender types
Makes the CommandAPI display a warning if it finds commands present in a plugin.yml file
Adds more helper methods to the Brigadier class
Adds a tree-like syntax for command declarations
Adds support for asynchronous suggestions
Rewrote how argument suggestions are declared, instead of lots of overloads, require a single object which encompasses the various different suggestion methods
Remove various deprecated safeOverrideSuggestions methods
Changed CommandAPI.fail() so it doesn't automatically throw the exception it generates