Show which line is Up-or downcast in Import SVP dialog
The Import Sound Velocity Profile dialog in the Echosounder Settings shows the up-and downcast (when available) in different colors.
Note that in the Options of the Import dialog it is possible to select whether to use only up-or down cast.
Add sound velocity from system to velocity profile
Most multibeam systems are able to measure the sound speed at the transducer. As this value is more up to date than the SVP, it makes sense to use the near real-time value for ray tracing.
A problem here is that the units do not really report the sound speed at the head, they report the sound speed at the head that they used to calculate the beam angles. When the unit is configured to use the real time sound velocity, this value will be equal to the actual sound velocity at the head, but there is also an option to set the sound velocity the unit uses by hand. In that case, the reported sound velocity may not match the actual sound velocity.
Because of this fact the usage of the sound velocity received from the unit is now a user configuration item.