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>

tests/vm_test_util.go

@@ -225,7 +225,7 @@ func RunVm(state *state.StateDB, env, exec map[string]string) ([]byte, vm.Logs,
 
 	caller := state.GetOrNewStateObject(from)
 
-	vmenv := NewEnvFromMap(RuleSet{params.MainNetHomesteadBlock, params.MainNetDAOForkBlock, true, nil}, state, env, exec)
+	vmenv := NewEnvFromMap(&params.ChainConfig{params.MainNetHomesteadBlock, params.MainNetDAOForkBlock, true, nil, common.Hash{}, nil}, state, env, exec)
 	vmenv.vmTest = true
 	vmenv.skipTransfer = true
 	vmenv.initial = true