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.
