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/gen/_template/struct.tmpl

@@ -0,0 +1,46 @@
+{{- /*gotype: go.mau.fi/mautrix-telegram/pkg/gotd/gen.structDef*/ -}}
+{{ define "struct" }}{{ $s := . }}
+// {{ $s.Comment }}
+{{- if $s.Docs }}
+{{- template "print_comment"  $s.Docs }}
+{{- end }}
+{{- if $s.Links }}
+    {{- template "print_links" $s.Links }}
+{{- end }}
+{{- if $s.URL }}
+//
+// See {{ $s.URL }} for reference.
+{{- end }}
+type {{ $s.Name }} struct {
+{{- range $f := $s.Fields }}
+{{- template "print_comment" $f.Comment }}
+{{- if $f.Links}}
+    {{- template "print_links" $f.Links }}
+{{- end }}
+{{- if and ($f.Conditional) (not $f.ConditionalBool) }}
+//
+// Use Set{{ $f.Name }} and Get{{ $f.Name }} helpers.
+{{- end }}
+    {{ $f.Name }} {{ template "print_type" $f }}
+{{- end }}
+}
+
+// {{ $s.Name }}TypeID is TL type id of {{ $s.Name }}.
+const {{ $s.Name }}TypeID = {{ if not $s.Vector }}0x{{ $s.HexID }}{{- else -}}bin.TypeVector{{- end }}
+
+{{ if $s.Interface }}
+// construct implements constructor of {{ $s.Interface }}.
+func ({{ $s.Receiver }} {{ $s.Name }}) construct() {{ $s.Interface }} { return &{{ $s.Receiver }} }
+{{ end }}
+
+// Ensuring interfaces in compile-time for {{ $s.Name }}.
+var (
+    _ bin.Encoder = &{{ $s.Name }}{}
+    _ bin.Decoder = &{{ $s.Name }}{}
+    _ bin.BareEncoder = &{{ $s.Name }}{}
+    _ bin.BareDecoder = &{{ $s.Name }}{}
+    {{ if $s.Interface }}
+    _ {{ $s.Interface }} = &{{ $s.Name }}{}
+    {{ end }}
+)
+{{ end }}