move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/bin/int128_test.go

@@ -0,0 +1,28 @@
+package bin
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestInt128_Encode(t *testing.T) {
+	a := require.New(t)
+
+	v := Int128{1, 2, 3, 0, 134, 45}
+	b := Buffer{}
+	a.NoError(v.Encode(&b))
+	var decoded Int128
+	a.NoError(decoded.Decode(&b))
+	a.Equal(v, decoded)
+	a.Error(decoded.Decode(&Buffer{}))
+}
+
+func BenchmarkBuffer_PutInt128(b *testing.B) {
+	v := Int128{10, 15}
+	buf := new(Buffer)
+	for i := 0; i < b.N; i++ {
+		buf.PutInt128(v)
+		buf.Reset()
+	}
+}