enhancement - add scales on the sonograms

[philippetournevase-spec]

1/ as option, add 1 metric scale on the speed corrected sonograms in the travel direction along the water surface line (0 at the begining)
2/ as option, add metric scales on the port and star sonograms in the lateral directions at the begining ping, zero at the water surface line
3/ as a sub option of the previous, add lines each 5 m for example (in the lateral directions) all along the port and star sonograms

[CameronBodine]

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