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/crypto/data_with_hash_test.go

@@ -0,0 +1,31 @@
+package crypto
+
+import (
+	"bytes"
+	mathrand "math/rand"
+	"testing"
+)
+
+func TestGuessData(t *testing.T) {
+	for _, s := range []string{
+		"a",
+		"foo",
+		"bar",
+		"wake up neo",
+		"24145",
+	} {
+		rnd := mathrand.New(mathrand.NewSource(239))
+		data := []byte(s)
+		dataWithHash, err := DataWithHash(data, rnd)
+		if err != nil {
+			t.Fatal(err)
+		}
+		guessed := GuessDataWithHash(dataWithHash)
+		if guessed == nil {
+			t.Fatal("got nil")
+		}
+		if !bytes.Equal(guessed, data) {
+			t.Fatal("invalid guess")
+		}
+	}
+}