Research task: create termPenaltyOnPledge method

[Schwartz10]

It's important to understand what new hypothetical termination penalties you will incur as a miner if you pledge new FIL.

The method interface:

termPenaltyOnPledge(filToPledge *big.Int, sectorSize uint64, percQAP *big.Float) => (cost *big.Int, penalty *big.Int, error)

cost - the cost to pledge the given sector (hypothetically)
penalty - the hypothetical term penalty on the sector

For the variables we need to supply to the TerminateSector call:

	height uint64 => current block height
	sectorSize uint64 => get from the miner ID
	qaPowerSmoothedPositionEstimate *corebig.Int => network params
	qaPowerSmoothedVelocityEstimate *corebig.Int => network params
	rewardSmoothedPositionEstimate *corebig.Int => network params
	rewardSmoothedVelocityEstimate *corebig.Int => network params
	activation uint64 => current block height
	expiration uint64 => hardcode to 18 months
	dealWeight *corebig.Int => hardcode to 0 for now
	verifiedDealWeight *corebig.Int => percQAP passed as a parameter
	expectedDayReward *corebig.Int => network parameter based on sector power
	expectedStoragePledge *corebig.Int => network parameter
	powerBaseEpoch uint64 => ???
	replacedDayReward *corebig.Int => IGNORE FOR NOW

NOTE that this does not have to do with any existing economics pledged in sectors for any particular single miner. It's helpful to understand how 1 FIL will devalue upon pledging

[jimpick]

PR #84 has a possible implementation for this.