Cnc: added mechanism for flushing queue. Incomplete.
Cnc.enqueue_str/notify now need to be called via external_request
Cnc: support the fact that requests may be dequeued at any time in the interface
CncControl: disabled movement limit
Align: Upload can now be cancelled
Cnc.tinyg_status: added field 'stat'
Cnc: for some reason needs to use future#set_if_unset instead of plain #set
Cnc: added ability to wait for a certain tinyg state
Cnc.flush_queue: use send_flush instead of send_raw_noresponse
Align: added ability to cancel upload
Use new version of OCamlGcode (nan-fix)
CncControl now tracks the CNC during upload
CncControl: viewport position is now to to the other way from coord mode offset.. maybe wrong, but at least consistent.