make overkill logic aware of overkill bonuses

[maurezen]

at the moment overkill logic doesn't know that you can overkill 4-6 cells. it should be aware of this to correctly estimate full overkill times and, consequently, correctly start buying more equips when overkill starts to fail.

[maurezen]

alternatively, that shortcutting logic should be aware of h/d ratio and start buying more stuff once it gets past mapping thresholds.