add wind and swell direction to das_process output

[smwoodman]

There are fields for WindSpdKt and SwellHght, but there should also be fields for WindDir & SwellDir.

WindDir is event W, field 4
SwellDir is event V, field 3

This will involve at least:

• updating das_process code and docs
• updating tests
• updating the classes?
• Making sure other functions (effort and sighting esp) will handle these new fields

[ericmkeen]

On my radar for LTAbundR and I will check to see if this impacts anything downstream.