This delta, adds an extra keyboard object to handle those keys that are not part of the main keyboard class.  In particular there are separate HID reports for some of the keys, such as Power keys, and multimedia keys.

These reports might be on separate Interface or in cases where the mouse and keyboard are on the same device, the extra reports may be on the Mouse Interface.

So far I have not tried to combine with Keyboard object as might require multiple inheritance which I would like to avoid.

Also I extended the special key mapping table to map several other keys like F1-12, Arrow, Home/end... To special values where the 0x80 bit is set.  I used the same values as used for the Arduino Keyboard library.  I did not use their defines as they used defines like KEY_F1, which already exists in core, but in core it is the scan code from the keyboard and not the end user value.

https://forum.pjrc.com/threads/45740-USB-Host-Mouse-Driver?p=155745&viewfull=1#post155745

PS3 - Right Joystick does not work

There is an issue with the extra items added to the report after the main known items.

Problem was HID report descriptor does something like:
Usage Page; Desktop  (01)
Usage: 01  (Pointer)
Count xxx

Problem is the Usage values below 0x20 appear to have some other standard meaning.   Which you can see in
http://www.usb.org/developers/hidpage/Hut1_12v2.pdf

So current fix is to ignore Usage values passed in < 0x20...
Appears to fix PS3 Right joystick

PS4 support

Had to increase size of HID report to 512.
Allow HAT to work 10039

Mouse Example prints out Z, Rz, Ry, Rx and Hat values

https://forum.pjrc.com/threads/45740-USB-Host-Mouse-Driver