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/message/internal/mkrun/generator.go

@@ -0,0 +1,15 @@
+package mkrun
+
+import "flag"
+
+// Generator represents generator script.
+type Generator interface {
+	// Name is generator name.
+	Name() string
+	// Flags sets generator flags.
+	Flags(set *flag.FlagSet)
+	// Template returns generation template.
+	Template() string
+	// Data returns associated generation data.
+	Data() (interface{}, error)
+}