Reducing InstantSend transaction fee

[bhkien]

Despite we have many merchants accepting Dash but number of transactions on chain still low.

I think reducing InstantSend fee would let people in countries like Venezuela feel easier to spend.

 

[InhumanPerfection]

I hope this Pull request will be adopted. And fees for most InstantSend transactions (with 1-4 inputs) will be as low as for ordinary transactions.