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/tgtest/buffered_test.go

@@ -0,0 +1,64 @@
+package tgtest
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/transport"
+)
+
+func TestBufferedConn(t *testing.T) {
+	a := assert.New(t)
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	i := transport.Intermediate
+	c1, c2 := i.Pipe()
+	b := newBufferedConn(c1)
+	defer func() {
+		a.NoError(b.Close())
+		a.NoError(c2.Close())
+	}()
+
+	payload := []byte("abcdabcd")
+	go func() {
+		b1 := &bin.Buffer{Buf: payload}
+		a.NoError(c2.Send(ctx, b1))
+	}()
+
+	// Test Recv before Push.
+	recvBuf := &bin.Buffer{}
+	a.NoError(b.Recv(ctx, recvBuf))
+	a.Equal(payload, recvBuf.Buf)
+
+	pushed := []byte("12345678")
+	b.Push(&bin.Buffer{Buf: pushed})
+	go func() {
+		b1 := &bin.Buffer{Buf: payload}
+		a.NoError(c2.Send(ctx, b1))
+	}()
+
+	// Test Push.
+	recvBuf.Reset()
+	a.NoError(b.Recv(ctx, recvBuf))
+	a.Equal(pushed, recvBuf.Buf)
+
+	// Test Recv after Push.
+	recvBuf.Reset()
+	a.NoError(b.Recv(ctx, recvBuf))
+	a.Equal(payload, recvBuf.Buf)
+
+	// Test send.
+	go func() {
+		b1 := &bin.Buffer{Buf: payload}
+		a.NoError(b.Send(ctx, b1))
+	}()
+
+	recvBuf.Reset()
+	a.NoError(c2.Recv(ctx, recvBuf))
+	a.Equal(payload, recvBuf.Buf)
+}