optimize png images losslessly via zopflipng

[PeterDaveHello]

Re-compress png images losslessly via Google's zopflipng.

parameters:
$ zopflipng --iterations=650 --lossy_transparent --splitting=3 --filters=01234mepb -y

result:

 api/apiCss/img/apiMenu.png            | Bin 3954 -> 3082 bytes
 api/apiCss/img/chinese.png            | Bin 1556 -> 724 bytes
 api/apiCss/img/close.png              | Bin 1908 -> 1639 bytes
 api/apiCss/img/contact-bg.png         | Bin 177 -> 116 bytes
 api/apiCss/img/english.png            | Bin 1356 -> 664 bytes
 api/apiCss/img/header-bg.png          | Bin 148 -> 103 bytes
 api/apiCss/img/lightbulb.png          | Bin 27355 -> 24706 bytes
 api/apiCss/img/overlay_arrow.png      | Bin 830 -> 482 bytes
 api/apiCss/img/overlay_bg.png         | Bin 109 -> 70 bytes
 api/apiCss/img/zTreeStandard.png      | Bin 12573 -> 8536 bytes
 css/metroStyle/img/line_conn.png      | Bin 933 -> 85 bytes
 css/metroStyle/img/metro.png          | Bin 5283 -> 2485 bytes
 css/zTreeStyle/img/diy/1_close.png    | Bin 601 -> 323 bytes
 css/zTreeStyle/img/diy/1_open.png     | Bin 580 -> 315 bytes
 css/zTreeStyle/img/diy/2.png          | Bin 570 -> 395 bytes
 css/zTreeStyle/img/diy/3.png          | Bin 762 -> 496 bytes
 css/zTreeStyle/img/diy/4.png          | Bin 399 -> 240 bytes
 css/zTreeStyle/img/diy/5.png          | Bin 710 -> 527 bytes
 css/zTreeStyle/img/diy/6.png          | Bin 432 -> 295 bytes
 css/zTreeStyle/img/diy/7.png          | Bin 534 -> 338 bytes
 css/zTreeStyle/img/diy/8.png          | Bin 529 -> 378 bytes
 css/zTreeStyle/img/diy/9.png          | Bin 467 -> 305 bytes
 css/zTreeStyle/img/zTreeStandard.png  | Bin 11173 -> 8111 bytes
 demo/cn/super/left_menuForOutLook.png | Bin 421 -> 222 bytes
 demo/en/super/left_menuForOutLook.png | Bin 421 -> 222 bytes

[PeterDaveHello]

@zTree would you please take a look at this one? Thanks!

[soakit]

smaller via limitpng
@PeterDaveHello @zTree

[PeterDaveHello]

@soakit zoplipng is "lossless" compression

[soakit]

so is limitpng @PeterDaveHello

[PeterDaveHello]

Okay, I read its document, it also uses zopflipng and some other tools.