* Adds a first pass of a LatLonPolyLine class that will be used to draw
the single line segment for a cross-section.
* Adds an LineCrossSection example.
* Adds some initial lasso-specific event handling for lasso shapes. This
currently captures lasso shape create, delete, and draggable edit begin,
end.
* Adds a new onDrawEvent() method to raster-draw-mixin that's used as a
conduit to adding event callbacks to the drawEngine instance that
manages all the drawn lasso shapes. There's room for improvement here
tho.
* Adds new LassoToolSetTypes bitflag enum to control the visibility of
which lasso tools you want to display on a raster-draw-mixin enabled
chart.
