core, core/state, trie: EIP158, reprice & skip empty account write

This commit implements EIP158 part 1, 2, 3 & 4

1. If an account is empty it's no longer written to the trie. An empty
  account is defined as (balance=0, nonce=0, storage=0, code=0).
2. Delete an empty account if it's touched
3. An empty account is redefined as either non-existent or empty.
4. Zero value calls and zero value suicides no longer consume the 25k
  reation costs.

params: moved core/config to params

Signed-off-by: Jeffrey Wilcke <jeffrey@ethereum.org>

miner/miner.go

@@ -62,7 +62,7 @@ type Miner struct {
 	shouldStart int32 // should start indicates whether we should start after sync
 }
 
-func New(eth Backend, config *core.ChainConfig, mux *event.TypeMux, pow pow.PoW) *Miner {
+func New(eth Backend, config *params.ChainConfig, mux *event.TypeMux, pow pow.PoW) *Miner {
 	miner := &Miner{
 		eth:      eth,
 		mux:      mux,