core: add new eip-1559 tx constraints

[zsfelfoldi]

This PR adds the new consensus constraints of EIP-1559 transactions as specified here:
ethereum/EIPs#3594
Note: the same sanity checks are performed first during tx pool validation even though the previously existing filters would filter out the same transactions. This way the same error types can be returned by the pool and by consensus.

[holiman]

LGTM
I pushed some minor changes, reducing the bigints in buygas, and making the big number exactly on the bitlength boundary.

[zsfelfoldi]

Please merge it if you have the necessary rights, I can't do that because of a random travis failure.

[holiman]

Odd, faucet_test.go:37: No Ethereum address found to fund -- failed on both appveyor jobs and one of the travis jobs. I can understand if it fails consistently on a platform where outgoing traffic is constrained, but I don't understand why it's flaky otherwise.

[holiman]

I had forgotten to push some of my changes. I squashed it into the last commit, ptal @zsfelfoldi

[holiman]

With these new rules in place, testing on baikal, I get

########## BAD BLOCK #########
Chain config: {ChainID: 1642 Homestead: 0 DAO: <nil> DAOSupport: true EIP150: 0 EIP155: 0 EIP158: 0 Byzantium: 0 Constantinople: 0 Petersburg: 0 Istanbul: 0, Muir Glacier: <nil>, Berlin: 0, London: 500, Engine: clique}

Number: 30084
Hash: 0x53805e3c841d3627555e13cd65d2f70cde22d44b73f6d884879b205a9b4e8dee


Error: could not apply tx 0 [0xd3a10c0327569f01245f89a2b435b26e40017ae7e94ac525467390899d18244d]: tip higher than fee cap: address 0xBaaDF00d42264eEb3FAFe6799d0b56cf55DF0F00, tip: 10000000000, feeCap: 340282366920938463463374607431768211455

Which seems correct