Added support for slider, dial and 4 hat switches

[gavazquez]

I implemented the changes of this PR: https://github.com/MHeironimus/ArduinoJoystickLibrary/pull/129 But I also added support for 4 hat switches (they are very useful for hotas controllers)

I also added a limit of 128 buttons as that's the maximum that HID supports

[MHeironimus]

Just curious if you have a reference for your statement "a limit of 128 buttons as that's the maximum that HID supports". My understanding was the limit was 0xFFFF (65535) based on what I have read in section 12 Button Page of the https://usb.org/sites/default/files/documents/hut1_12v2.pdf, but I don't think many applications/operating systems can actually see that many. The library supports up to 255, but most applications cannot see that many. There is a section about this in the FAQ (https://github.com/MHeironimus/ArduinoJoystickLibrary/wiki/FAQ).

[gavazquez]

You're right. The app I was using couldn't see past 128 buttons and I saw that some other people took that limit aswell so I assumed that it was the standard.

The 4 hat switches are useful tough since many high end joysticks have them: https://virpil.com/images/2019/02/16/MT-50CM2_02.png