4.0.0 - Githubissues

Contains all planned changes for 4.0.0

Source Code Changes

Added support for Treasury.
Added currency support in the config.
Added HeadSubCommand for sub-commands.
Added all sub-commands to their respective classes.
Renamed HeadDatabase#updateAsync to HeadDatabase#update.
Renamed HeadDatbase#getHeadsNoCacheAsync to HeadDatabase#getHeadsNoCache.
Renamed CommandHeadDB to HeadDBCommand.
Renamed HEconomyProvider to BasicEconomyProvider.
Moved event classes to api/event.
Moved database classes to implementation.
Moved Head and LocalHead to implementation.
HeadAPI will now use streams to filter results.
Return unmodifiable list of HeadDatbase#getHeads(category).
Payments are now handled asynchronously (Additionally, users will now receive a "purchasing..." message).
Utils now has a async(task) method.

The project will now follow Semantic Versioning.
From now on new additions to the source code should be documented with the @since <version> tag.
The project will most likely have a changelog starting from 4.0.0.