Improve AutoOverlord so that zerg bots won't easily get supplyblocked

[DrInfy]

Take into account amount of larva, income and available resources to determine whether a new overlord should be build or not.

[august-k]

I think it should also look at the the durations left on Inject Larva/the base larva cycle of the Hatchery. There may be enough supply and larva for the current round of production, but if that production brings you to the supply cap, you'll be blocked when the next round of larva spawns and have to wait for an Overlord. Therefore, you'd need to build an Overlord on the current round of production despite having enough supply.

[DrInfy]

if the optimization works decently, we could use a modifier for extra overlords, like +1 or +2 more than what is actually required in case an existing overlord or overseer dies or is send to scout.