export Transfor Matrix in toObject

[asturur]

closes #2333

Do not really know if we should export everything, but transformMatrix is crucial when exporting pathGroups.

[asturur]

Other proposed solution:

PathGroup.toObject changes:

    toObject: function(propertiesToInclude) {
      !propertiesToInclude && propertiesToInclude = [ ];
      propertiesToInclude.push('transformMatrix');
      var o = extend(parentToObject.call(this, propertiesToInclude), {
        paths: invoke(this.getObjects(), 'toObject', propertiesToInclude)
      });
      if (this.sourcePath) {
        o.sourcePath = this.sourcePath;
      }
      return o;
    },

[asturur]

@kangax what do you say?

[kangax]

It's the kind of property that affects object representation (not controls or behavior) so we should definitely export it!

[asturur]

@kangax you can merge now.

All tests are passing but not this:

Module: fabric.Image Test: crossOrigin
toObject should return proper crossOrigin value
    at /home/travis/build/kangax/fabric.js/test/unit/image.js:182:7
    at /home/travis/build/kangax/fabric.js/test/unit/image.js:58:7
    at /home/travis/build/kangax/fabric.js/test/unit/image.js:75:21
    at fs.js:272:14
    at Object.oncomplete (fs.js:108:15)
Actual value:
undefined
Expected value:

This is because of the latest commit i was discussing with you.
So i'm not fixing this test as of now, waiting for you.
i still belive you introducd some breaking changes because those properties you removed ( crossOrigin, alignX, alignY and meetOrSlice are not handled by any export function anymore ).