Robot: remove unused variable
USB DFU: keep usb connected while we respond to reset request.

we also become a kernel module so we can receive the on idle event. This would be an ideal place to do shutdown tasks, eg save position somewhere
Extruder: make sure we have a block to release, avoid segfaults
Turn ringbuffer around the regular way, add some utility methods to avoid needless new/delete to fill queue
block queue shuffle, requires further testing to see if this prevents the queue stopping, does not fix G93 bug
Merge remote-tracking branch 'origin/block_queue_shuffle' into ben-edge