Uses Snap Rounding to compute a rounded, fully noded arrangement from a set of
SegmentStrings. Implements the Snap Rounding technique described in papers by Hobby, Guibas & Marimont, and Goodrich et al. Snap Rounding assumes that all vertices lie on a uniform grid; hence the precision model of the input must be fixed precision, and all the input vertices must be rounded to that precision.
This implementation uses a monotone chains and a spatial index to speed up the intersection tests.
This implementation appears to be fully robust using an integer precision model. It will function with non-integer precision models, but the results are not 100% guaranteed to be correctly noded.