Optimize centroid calculation rubber sheet

[bmarchant]

Rubbersheeting buildings used the centroid of the polygon as the tie-point but converted the building element into a geos::geom::Geometry object before calling the built-in getCentroid() function. This conversion is heavy so a heuristic approach of using the average of all coordinates in the element, recursively for any relations. While the binary .rs file changed in the AlignApplyCmdTest unit test, the results were the same when the input was rubbersheeted.

While in the ElementGeometryUtils code, the calculateLength function had a similar issue of converting linear ways to geos::geom::Geometry objects. I used simple iterative distance calculations on way segments to replace the conversion.