Pins offsets are now exported as floats
First attempt (buggy) at MCF-based position optimization
Slightly better orientation algorithm

* Retries cells that may have changed optimal orientations
Orientation code cleanup

* Non-replicated code to handle both x and y optimization
* Correction Movable -> Flippable
* Tests between stack and queue
Bug correction

* Unbounded arcs with negative cost are present
* Cost scaling assumes that the problem is unbounded
* Now uses an artificial capacity
* Both network simplex and cost/capacity scaling are still too slow
Working minimum-cost flow optimization

* Still extremely slow (~2h on bigblue1)
* Particularly inefficient (-0.2% wirelength on the result of the global placement)
Merge branch 'MCF', which provides fixed-topology optimization