Update method fix

[cduff4464]

As was brought up in the issue I created, there is currently no method for the CrossSectionMainWindow class. This pull request simply creates a method for this class to add new data to the cross section viewer.

[CJ-Wright]

FYI you can reference a PR or issue by using the # sign. For example the issue mentioned is #84

[CJ-Wright]

Doc strings in this would be appreciated. Please use the numpy doc string format.

[CJ-Wright]

Have you not written tests for this addition?

[CJ-Wright]

Also it seems that the travis.yml file has some issues @tacaswell @danielballan have you seen these errors before?

[tacaswell]

👍 , mostly agree with @CJ-Wright 's comments. The classes in this code are a bit out of control, I would not do them this way again if starting from scratch.

It looks like much of this logic should fall back to the Messenger class and the code at this level. should mostly delegate (you should not be reaching in to do self._messenger._ctrl_widget._spin_img.setMaximum(len(self.key_list)-1) as that is going across 3 layers of things telling you they are 'private').

[tacaswell]

to fix the travis issue, change the channel from scikit-xray -> scikit-beam (test that locally to make sure I remembered the name right).

[tacaswell]

And if doing the messenger stuff 'right' turns into a complete hairball, I would lean on the side of just making this work.

[mrakitin]

What's the status of this PR?