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/fields_test.go

@@ -0,0 +1,40 @@
+package bin
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFields(t *testing.T) {
+	t.Run("Encode", func(t *testing.T) {
+		a := require.New(t)
+		var f Fields
+
+		a.True(f.Zero())
+		f.Set(1)
+		f.Set(0)
+		f.Set(10)
+		f.Unset(10)
+		f.Set(5)
+		a.True(f.Has(1))
+		a.True(f.Has(5))
+		a.True(f.Has(0))
+		a.False(f.Has(2))
+		a.False(f.Has(10))
+		a.Equal("100011", f.String())
+
+		var b Buffer
+		a.NoError(f.Encode(&b))
+		var decoded Fields
+		a.NoError(decoded.Decode(&b))
+		a.Equal(f, decoded)
+	})
+
+	t.Run("Decode", func(t *testing.T) {
+		a := require.New(t)
+
+		var decoded Fields
+		a.Error(decoded.Decode(&Buffer{}))
+	})
+}