Refactored standard AisTarget portrayal graphics into VesseTriangleGraphic to allow for VesseTargetGraphic to chose between different graphics in order to better allow changes to how AisTargets are displayed depending on zoom level.
Working prototype of ship outline for AisLayer. Includes new ZoomLevel enum used to decipher how to draw Vessels.
Added display of vessels as "dots" when zoomed far out.
Merge branch 'master' of https://github.com/dma-enav/EPD