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/query/hasher/hash.go

@@ -0,0 +1,30 @@
+// Package hasher contains Telegram pagination hash implementation.
+package hasher
+
+// Hasher implements Telegram pagination hash counting.
+//
+// See https://core.telegram.org/api/offsets#hash-generation.
+type Hasher struct {
+	state uint32
+}
+
+// Reset resets the Hasher to its initial state.
+func (h *Hasher) Reset() {
+	h.state = 0
+}
+
+// Update performs state change using given value.
+func (h *Hasher) Update(value uint32) {
+	h.state = (h.state * 20261) + value
+}
+
+// Update64 performs state change using given 64-bit value.
+func (h *Hasher) Update64(value uint64) {
+	h.Update(uint32(value >> 32))
+	h.Update(uint32(value & 0xFFFFFFFF))
+}
+
+// Sum returns final sum.
+func (h *Hasher) Sum() int64 {
+	return int64(h.state & 0x7FFFFFFF)
+}

pkg/gotd/telegram/query/hasher/hash_test.go

@@ -0,0 +1,18 @@
+package hasher
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestHasher(t *testing.T) {
+	hasher := Hasher{}
+	data := []int{7, 5, 16, 8}
+
+	for i := range data {
+		hasher.Update(uint32(data[i]))
+	}
+
+	require.Equal(t, int64(611477280), hasher.Sum())
+}