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/bin/pool.go

@@ -0,0 +1,44 @@
+package bin
+
+import "sync"
+
+// Pool is a bin.Buffer pool.
+type Pool struct {
+	pool sync.Pool
+}
+
+// NewPool creates new Pool.
+// Length is initial buffer length.
+func NewPool(length int) *Pool {
+	return &Pool{
+		pool: sync.Pool{
+			New: func() interface{} {
+				var r []byte
+				if length > 0 {
+					r = make([]byte, 0, length)
+				}
+				return &Buffer{Buf: r}
+			},
+		},
+	}
+}
+
+// Put returns buffer to pool.
+func (b *Pool) Put(buf *Buffer) {
+	b.pool.Put(buf)
+}
+
+// Get takes buffer from pool.
+func (b *Pool) Get() *Buffer {
+	buf := b.pool.Get().(*Buffer)
+	buf.Reset()
+	return buf
+}
+
+// GetSize takes buffer with given size from pool.
+func (b *Pool) GetSize(length int) *Buffer {
+	buf := b.Get()
+	buf.ResetN(length)
+
+	return buf
+}