Align: refer to tool position with the name 'tool', not 'cnc'

Current CNC position can be different from the tool position.
In future we want to use only tool position for everything.
CncControl: support different coordinate modes (tool/camera)
CncControl: use with_cnc for accessing the optional cnc value
CncControl: added ability to adjust camera offset
Align.coordinate_translation: actually use the translation variable
Align.coordinate_transformation: dropped the unused translation variable
Align.gui: use CncControl's mechanism for camera/tool difference
CncControl: handle offsets properly. Maybe.