improvment - merging and reorienting port and star sonograms

[philippetournevase-spec]

incorporate an option to get an image by merging the port and star sonograms (non georectified) with port on left, starboard on right, most recent return on top, first return on bottom and water column present (like deep view fv for example).

[CameronBodine]

Thank you for the recommended enhancement! I will update as time allows.