ModelGeometry division by 0.0 for a single ellipsoid shape

[Maciej Komosinski]

For the following structure/genotype:

Simulator.print(ModelGeometry.forModel(Model.newFromString("//0\np:sh=1\n")).area());

in externalAreaOfSurface(), in the second iteration of

	while (surface.tryGetNext(point))

In function

void MeshBuilder::EllipsoidSurface::findNextAreaEdgeAndPhase()

There is div by 0.0 (invalid FP operation) because edge.x and edge.z are 0.0:

limit.z = edge.z*edge.z / sqrt(edge.x*edge.x + edge.z*edge.z);

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Similar defect to fix: numerous sqrt: DOMAIN error exceptions when running geometry unit tests.

[oriona]

In 539:

Division by 0.0 for a single ellipsoid fixed [closes #42]. Sampling the same point twice fixed.

[oriona]

In 541:

Division by 0.0 for a single ellipsoid fixed [closes #42]. Sampling the same point twice fixed.