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>

core/state/state_test.go

@@ -48,7 +48,7 @@ func (s *StateSuite) TestDump(c *checker.C) {
 	// write some of them to the trie
 	s.state.updateStateObject(obj1)
 	s.state.updateStateObject(obj2)
-	s.state.Commit()
+	s.state.Commit(false)
 
 	// check that dump contains the state objects that are in trie
 	got := string(s.state.Dump())
@@ -100,7 +100,7 @@ func TestNull(t *testing.T) {
 	//value := common.FromHex("0x823140710bf13990e4500136726d8b55")
 	var value common.Hash
 	state.SetState(address, common.Hash{}, value)
-	state.Commit()
+	state.Commit(false)
 	value = state.GetState(address, common.Hash{})
 	if !common.EmptyHash(value) {
 		t.Errorf("expected empty hash. got %x", value)
@@ -160,7 +160,7 @@ func TestSnapshot2(t *testing.T) {
 	so0.deleted = false
 	state.setStateObject(so0)
 
-	root, _ := state.Commit()
+	root, _ := state.Commit(false)
 	state.Reset(root)
 
 	// and one with deleted == true