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/pool/options.go

@@ -0,0 +1,19 @@
+package pool
+
+import "go.uber.org/zap"
+
+// DCOptions is a Telegram data center connections pool options.
+type DCOptions struct {
+	// Logger is instance of zap.Logger. No logs by default.
+	Logger *zap.Logger
+	// MTProto options for connections.
+	// Opened connection limit to the DC.
+	MaxOpenConnections int64
+}
+
+func (d *DCOptions) setDefaults() {
+	if d.Logger == nil {
+		d.Logger = zap.NewNop()
+	}
+	// It's okay to use zero value for MaxOpenConnections.
+}