Enforce min gas fee for all transactions

[blockcreators]

Because smart contracts might use transaction information, we cannot just archive older chain states and start fresh.
So it might be good to have a minimum transaction fee. This would reduce spamming the chain with 0 fee transactions, thus filling up the chain state with useless transaction data.

[JakeHartnell]

Network was able to be brought down with an attack from a malicious smart contract. This needs to be done.

[blockcreators]

Would be ideal to have the fee as a parameter so that governance can auto change it via voting.

[faddat]

Hot

[the-frey]

Don't disagree about it being changed by governance, but if governance changes it to 0 for zone reason then the network is ☠️

[blockcreators]

Don't disagree about it being changed by governance, but if governance changes it to 0 for zone reason then the network is ☠️

Governance could also vote to mint 1 trillionzillion coins and do the same thing :)

[the-frey]

This is superceded by #82

[JakeHartnell]

Network was able to be brought down with an attack from a malicious smart contract. This needs to be done.

In hindsight, not sure if this is needed. #82 should be enough. More risk from messing with this IMO.