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/updates/sort_pts.go

@@ -0,0 +1,82 @@
+package updates
+
+import (
+	"sort"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+func sortUpdatesByPts(u []tg.UpdateClass) {
+	sort.Stable(ptsSorter(u))
+}
+
+type ptsSorter []tg.UpdateClass
+
+func (p ptsSorter) Len() int {
+	return len(p)
+}
+
+func (p ptsSorter) Less(i, j int) bool {
+	type (
+		ptsType int
+		compare struct {
+			typ       ptsType
+			channelID int64
+			ptsDiff   int
+		}
+	)
+	// Sorting order
+	//
+	// 0) Common updates without PTS.
+	// 1) Common PTS updates
+	// 2) Common QTS updates
+	// 3) Channel PTS updates (by channelID and by pts)
+	const (
+		other ptsType = iota
+		commonPts
+		commonQts
+		channelPts
+	)
+	getType := func(u tg.UpdateClass) compare {
+		if pts, ptsCount, ok := tg.IsPtsUpdate(u); ok {
+			return compare{typ: commonPts, ptsDiff: pts - ptsCount}
+		}
+		if channelID, pts, ptsCount, ok, _ := tg.IsChannelPtsUpdate(u); ok {
+			return compare{typ: channelPts, channelID: channelID, ptsDiff: pts - ptsCount}
+		}
+		if qts, ok := tg.IsQtsUpdate(u); ok {
+			return compare{typ: commonQts, ptsDiff: qts}
+		}
+		return compare{typ: other}
+	}
+
+	a, b := getType(p[i]), getType(p[j])
+	switch {
+	case a.typ < b.typ:
+		return true
+	case a.typ > b.typ:
+		return false
+	}
+
+	// a.typ == b.typ
+	switch a.typ {
+	case other:
+		// Keep original order
+	case commonPts, commonQts:
+		return a.ptsDiff < b.ptsDiff
+	case channelPts:
+		if a.channelID < b.channelID {
+			return true
+		}
+		if a.channelID > b.channelID {
+			return false
+		}
+		return a.ptsDiff < b.ptsDiff
+	}
+
+	return false
+}
+
+func (p ptsSorter) Swap(i, j int) {
+	p[i], p[j] = p[j], p[i]
+}