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/cmd/rsagen/_template/main.tmpl

@@ -0,0 +1,50 @@
+// Code generated by rsagen, DO NOT EDIT.
+//
+{{ range .InputLines -}}
+// {{ printf "%s" . }}
+{{ end -}}
+//
+
+package {{ .Package }}
+
+import (
+	"crypto/rsa"
+	"math/big"
+)
+
+var _ = (*big.Int)(nil)
+
+{{ define "chunks" -}}
+	{{- range chunks . 8 }}
+		{{ range . }}{{ printf "%#02x" . }},{{ end }}
+	{{- end }}
+{{- end }}
+
+{{ define "bigint-positive" -}}
+	new(big.Int).SetBytes([]byte{
+		{{- template "chunks" .Bytes }}
+	})
+{{- end }}
+
+{{ define "bigint" }}
+	{{- if eq .Sign -1 -}} new(big.Int).Neg( {{- end -}}
+	{{- template "bigint-positive" . -}}
+	{{- if eq .Sign -1 -}} ) {{- end -}}
+{{ end }}
+
+{{ define "pubkey" -}}
+	&rsa.PublicKey{
+		E: {{ .E }},
+		N: {{ template "bigint" .N }},
+	}
+{{- end }}
+
+{{ if not .Single }}
+	var {{ .Variable }} = []*rsa.PublicKey{
+		{{- range .Keys }}
+			{{ template "pubkey" . }}, // Fingerprint: {{ fingerprint . }}
+		{{- end }}
+	}
+{{ else }}
+	var {{ .Variable }} = {{ template "pubkey" (single .Keys) }} // Fingerprint: {{ single .Keys | fingerprint }}
+{{ end }}