MustGetGasSettings reads GasPrice and GasAdjustment from app.toml file.

ValidateBTCHeader Perform the checks that [checkBlockHeaderSanity](https://github.com/btcsuite/btcd/blob/master/blockchain/validate.go#L430) of btcd does We skip the "timestamp should not be 2 hours into the future" check since this might introduce undeterministic behavior.