Add IsOnCurve check to EC unmarshalling in ECIES decryption

Transaction pool will attempt to ignore invalid transactions it had
previously encountered.

Forward and log EC recover err and remove dup pubkey len check

libsecp256k1 #define NDEBUG

Merge branch 'update_bitcoin_secp256k1_lib2' of https://github.com/Gustav-Simonsson/go-ethereum into Gustav-Simonsson-update_bitcoin_secp256k1_lib2

fixed printing circular structures

* miner control moved to `admin.miner`
* miner option to set extra data
* block extra now bytes

@zelig we need to discuss this

@zelig look in to this please