Fix compatibility with hubs and HID devices

[ChrisDeadman]

I needed to make those fixes in order to get the following combination of devices to work:

               Arduino SAMD
                    |
  [XBOXRCV] --- [USB HUB] --- [HIDUniversal Joystick]
                    |                           
             [HIDBOOT Mouse]

Also hotplug was a big issue for me which now works in my case - still not perfect though, when the hotplug process is interrupted (by pulling out the usb connector during device enumeration) the hub needs to be reconnected but this is a hard limitation of the USB host shield library in itself.
This might also resolve the USB Midi Host with HUB Problems.

[ChrisDeadman]

it does things a bit differently than this Pull Request for the original library but after a lot of debugging I found that there were issues with the address mapping of the connected devices, also they were not freed correctly.