Splitting JDA-Utilities into multiple packages

[Almighty-Alpaca]

There are 5 modules:

• jda-utilities-commons: common utility classes, event waiter
• jda-utilities-command: command client and
• jda-utilities-examples: the example commands
• jda-utilities-doc: the doc generator
• jda-utilities-menu: the menus

There's also the parent module jda-utilities that includes all 5 child modules and thus adds the while lib just as it used to before.

[Almighty-Alpaca]

Reminder to myself: produce javadocs for everything together

[Shengaero]

lgtm, @jagrosh feel free to merge whenever 👍