Move fin rendering into separate class
further organize fin rendering
Add cross product to Coordinate class
Working on edged fins
Remove extra points from finPointsWithTab: If the tab were even with the
front or back of the fin one or two duplicate points would appear in the
array.
Better fin tab rendering
Honor cross section setting
Make the bevel on the edge a set percentage of the fin length, not a set
value.
Some pretty subtle differences between rounded and airfoil, and a 
smooth edge on elipsoidal fins.
Transition shoulder thickness & factor out tube rendering.