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/cmd/mtprint/main.go

@@ -0,0 +1,31 @@
+// Binary mtprint pretty-prints MTProto message from binary file.
+package main
+
+import (
+	"flag"
+	"io"
+	"os"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/proto/codec"
+)
+
+func main() {
+	inputName := flag.String("f", "", "input file (blank for stdin)")
+	format := flag.String("format", "go", "print format")
+	flag.Parse()
+
+	var reader io.Reader = os.Stdin
+	if *inputName != "" {
+		f, err := os.Open(*inputName)
+		if err != nil {
+			panic(err)
+		}
+		defer func() { _ = f.Close() }()
+		reader = f
+	}
+
+	p := NewPrinter(reader, formats(*format), codec.Intermediate{})
+	if err := p.Print(os.Stdout); err != nil {
+		panic(err)
+	}
+}