3 col transitions

...e third column

Hi Roman,

In preparation for the visualization and other widgets being shown in the middle of the results page, I improved the expanding column interaction on the results page in a few ways:
* made 3rd col collapse into first col when screen is tablet sized
* added a model to keep track of which columns are open and which are closed
* now there is a method for the page manager to call to make the center column full width or return it to default size.

I did two things that you might not like : the page manager 3 column view is listening to the window resize event--I think I should change this to a single app listener on window events that other widgets can subscribe to.
I also had the problem that right now the "show" event is being triggered on page layouts before they are actually in the dom, so for now I re-triggered the event in the master page manager's "onSelectedChange" function. I also added a "detach" event.
But the show call in the child will be triggered before it is actually in the dom, right? I mean in the screen the user is seeing.
Right now the only reason i care is I'm measuring the width of the viewport using a media query, (for the 3 column adjustment) and that doesn't work until the view is actually residing in the dom. Other reasons you might want to know when the view actually arrives in the dom is for animations, though I can see this is not applicable to most widgets.