Add message for returning the current stage position.
Add (optional) cross hair to indicate the current stage position.
Fix some typos in the comments.
Change screen_id to display 2.
Merge branch 'master' into steve_track
Change to return current stage position as a coord.Point object.
Fix mosaic label so that it (hopefully) is in register with HAL regarding positions. Fix stage tracking so that the cross-hair is drawn in the correct position.
Resize cross-hair when zooming so that it is always the same size.
Change cross-hair color to blue.