image: add support for image/jpeg and image/png (#303)

* Copy from go1.17 image package
* Remove unnecessary files
* Reduce memory usage
* Add examples/ili9341/slideshow
* image: add ./image/README.md
* image: change convert2bin to . /cmd
* Makefile: add ./cmd to NOTEST

image/internal/compress/zlib/example_test.go

@@ -0,0 +1,37 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package zlib_test
+
+import (
+	"bytes"
+	"compress/zlib"
+	"fmt"
+	"io"
+	"os"
+)
+
+func ExampleNewWriter() {
+	var b bytes.Buffer
+
+	w := zlib.NewWriter(&b)
+	w.Write([]byte("hello, world\n"))
+	w.Close()
+	fmt.Println(b.Bytes())
+	// Output: [120 156 202 72 205 201 201 215 81 40 207 47 202 73 225 2 4 0 0 255 255 33 231 4 147]
+}
+
+func ExampleNewReader() {
+	buff := []byte{120, 156, 202, 72, 205, 201, 201, 215, 81, 40, 207,
+		47, 202, 73, 225, 2, 4, 0, 0, 255, 255, 33, 231, 4, 147}
+	b := bytes.NewReader(buff)
+
+	r, err := zlib.NewReader(b)
+	if err != nil {
+		panic(err)
+	}
+	io.Copy(os.Stdout, r)
+	// Output: hello, world
+	r.Close()
+}