store ids rather than Types in the structs so they can be encoded.

change Type to gobType.
fix some bugs around recursive structures.
lots of cleanup.
add the first cut at a type encoder.

R=rsc
DELTA=400  (287 added, 11 deleted, 102 changed)
OCL=31401
CL=31406

src/pkg/gob/encoder_test.go

@@ -0,0 +1,37 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gob
+
+import (
+	"bytes";
+	"gob";
+	"os";
+	"reflect";
+	"strings";
+	"testing";
+	"unsafe";
+)
+
+type ET2 struct {
+	x string;
+}
+
+type ET1 struct {
+	a int;
+	et2 *ET2;
+	next *ET1;
+}
+
+func TestBasicEncoder(t *testing.T) {
+	b := new(bytes.Buffer);
+	enc := NewEncoder(b);
+	et1 := new(ET1);
+	et1.a = 7;
+	et1.et2 = new(ET2);
+	enc.Encode(et1);
+	if enc.state.err != nil {
+		t.Error("encoder fail:", enc.state.err)
+	}
+}