[Suggestion] Add cropping function in a breeze(Windows platform).

[wsd1]

nircmd.exe savescreenshot support crop natively.

win32.js line7:

var nircmd = childProcess.spawn(path.join(__dirname, "bin", "nircmd.exe"), ["savescreenshot", options.output, options.x, options.y, options.w, options.h ]);	

So you can just call:

screenshot("screenshot.jpg", {x: 20, y: 0, w: 450, h: 1000}, function(error, complete) {});