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

@zelig this will need updating with the TD checking