Dithering module added (#617)

src/modules/Dither/Module.js

@@ -0,0 +1,37 @@
+module.exports = function Dither(options, UI){
+
+    var output;
+
+    function draw(input,callback,progressObj){
+
+        progressObj.stop(true);
+        progressObj.overrideFlag = true;
+
+        var step = this;
+
+        function extraManipulation(pixels) {
+            pixels = require('./Dither')(pixels, options.dither)
+            return pixels
+        }
+
+        function output(image,  datauri, mimetype){
+            // This output is accessible by Image Sequencer
+            step.output = { src: datauri, format: mimetype };
+
+        }
+
+        return require('../_nomodule/PixelManipulation.js')(input, {
+            output: output,
+            extraManipulation: extraManipulation,
+            format: input.format,
+            image: options.image,
+            callback: callback
+        });
+    }
+    return {
+        options: options,
+        draw: draw,
+        output: output,
+        UI: UI
+    }
+}