* New: Rectilinear::asRectangles(), decompose the Rectilinear into a
set of non-overlapping rectangles sliced vertically.
This not a mathematical minimum set. But should be speedier.
Done using a sweepline processing the vertical edges.
Specially suited for use in the extractor which basically
manage only rectangles.
Simple algorithm described in pp. 9-11 of Extractor notebook.
Tests done with unitests/python/test_rectilinear.py, the
Rectilinear here should cover all the sweepline cases.
Jean-Paul Chaput