added WriteVarInt64 ReadVarInt64

bin_test.go

@@ -3,7 +3,6 @@ package bin
 import (
 	"bytes"
 	"fmt"
-	"math"
 	"strconv"
 	"testing"
 	"time"
@@ -655,7 +654,11 @@ func TestInt32(t *testing.T) {
 
 	byteOrder := HL
 
-	err := WriteInt32(buf, ^math.MaxInt32, byteOrder)
+	//var origin int32 = -2147483648
+	//var origin int32 = math.MaxInt32
+	var origin int32 = 12141132
+
+	err := WriteInt32(buf, origin, byteOrder)
 	if err != nil {
 		t.Fatal(err)
 	}