Fix demos based on the device mode HID class driver, as well as the driver itself...

Fix demos based on the device mode HID class driver, as well as the driver itself. Changed HID device class driver to require the user to give a buffer and size to hold the previously generated report, for comparison purposes, and altered the prototype of the CALLBACK_HID_Device_CreateHIDReport() function so that reports can be sent to the host even if there are no apparent changes (useful for relative movements in mice, etc.).