Fix link to build instructions in the readme

Conflicts:
	rpc/responses.go

Blocktests are now integrated in cmd/ethereum.

The generic pointer decoder did not advance the input position
for empty values. This can lead to strange issues and even
infinite loops.

Merge branch 'frontier/blockpool' of https://github.com/ethersphere/go-ethereum into ethersphere-frontier/blockpool

Conflicts:
	rpc/api.go

I don't see why we would need two different accessors for a public field.

This makes Value 24 bytes smaller on 64bit systems.

Value.{Encode,Decode} are gone. It implements rlp.Encoder and rlp.Decoder
instead, so Value can be decoded into directly.

This seems to be the last remaining use of it.