Updates to V2 vessel traffic processing

[kellykapsar]

• Add towing vessels into tug category
• Add destinations into vector files (?)
• Mask out-of-bound pixels out of rasters

[kellykapsar]

Also changed definition of nighttime to civil twilight instead of sunrise/sunset.

[kellykapsar]

Other changes include:

• New vessel type categories: Cargo, Tanker, Fishing, Recreation (Passenger + Pleasure + Sailing), Military, TugTow, Other, Unknown
• Ship_Type code in vector data
• Remove gaps between line segments if the reason for segmenting them was change in time of day or change in motion (moving vs. stopped). Still kept gaps if they were due to gaps in transmission of > 6 hours or 60 km.
• Created vessel movement indicator: Vessels are considered stopped if their speed has been <3 knots for > 1 hour.