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/telegram/dcs/example_test.go

@@ -0,0 +1,52 @@
+package dcs_test
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"golang.org/x/net/proxy"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/telegram"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/telegram/dcs"
+)
+
+func ExampleDialFunc() {
+	// Dial using proxy from environment.
+
+	// Creating connection.
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	defer cancel()
+	client := telegram.NewClient(1, "appHash", telegram.Options{
+		Resolver: dcs.Plain(dcs.PlainOptions{Dial: proxy.Dial}),
+	})
+
+	_ = client.Run(ctx, func(ctx context.Context) error {
+		fmt.Println("Started")
+		return nil
+	})
+}
+
+func ExampleDialFunc_dialer() {
+	// Dial using SOCKS5 proxy.
+
+	sock5, _ := proxy.SOCKS5("tcp", "IP:PORT", &proxy.Auth{
+		User:     "YOURUSERNAME",
+		Password: "YOURPASSWORD",
+	}, proxy.Direct)
+	dc := sock5.(proxy.ContextDialer)
+
+	// Creating connection.
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	defer cancel()
+	client := telegram.NewClient(1, "appHash", telegram.Options{
+		Resolver: dcs.Plain(dcs.PlainOptions{
+			Dial: dc.DialContext,
+		}),
+	})
+
+	_ = client.Run(ctx, func(ctx context.Context) error {
+		fmt.Println("Started")
+		return nil
+	})
+}