Added first version of the new backward tracking method. It is now possible to use interpolation methods as well.

Integrated the empiric_offset and empiric_drift parameter of the float, Changed copy offsets layout.

The measured soundspeed is now being updated on applying a status to temperature and pressure, as well as on loading an rfb file.

The save feature for offsets in trajectory does work now. It was
already implemented, but did not work because of the variable name.