Added support for HTC Vive trackers.

[matzman666]

HTC released tracking pucks for their virtual reality system that allows third-parties to easily create accessories for virtual reality applications. One of the features of these trackers is that they can be connected via USB to accessories and allow them to send input events to the PC via the USB connection. Arduino provides a great platform to implement DIY accessoirs and that's why I added support for this to the USBHost library.

[tlf30]

This looks great, who needs to review it to get it merged?

[CLAassistant]

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