We where moving up segments in non-preferred direction attached to terminals. As those where fixed axis we got M3 with fixed axis in conflict with normal vertical M3. This is unsolvable. Don't do it!
Change: In GCell::stepNetDesaturate(), never move up a segment in non-preferred direction as they are usually attached to terminals, so they won't reduce the GCell density anyway.
Change: In LayerAssign::RpsInRow::slacken(), do not slacken horizontals from M1 vertical terminals when they are tall enough. Arbitrarily choose above 6 H-tracks (should be made a configuration parameter).
Change: In DataNegociate::update(), when processing perpandicular, we were taking into account "fixed axis" even when they were reduced (so not in tracks). Now do not.
We where moving up segments in non-preferred direction attached to terminals. As those where fixed axis we got M3 with fixed axis in conflict with normal vertical M3. This is unsolvable. Don't do it!