* If you load the squire.js script into a top-level page rather than an iframe,
it will add a Squire constructor to the global scope.
* The Squire constructor can be used to instantiate multiple instances on the
same page without having to load/parse/execute the full code every time.
* For each instance, create a new iframe, then call `new Squire( document )`,
with the document node for each iframe.
If you copy a portion of text from word, it includes an image version of the text as well as an HTML version. On paste, we now ignore the image
representation on the clipboard if an HTML representation is present, so that
the text pastes as expected, rather than as an image.
If you removed an event listener whilst it was being fired, this would alter the
list of handlers, which would cause the fireEvent function to read past the end
of the array (and to skip the next listener). Now, we clone the array of
listeners before firing, so adding/removing listeners has no effect on an
already firing event.
Firefox incorrectly goes back/forward in history instead of moving the cursor to
the beginning/end of the line when you press cmd-left/right on a mac. We now
override this to do the right thing.
When cleaning up pasted content, we remove any empty inline tags. However, we
should not be stripping <img> tags (which are of course both inline and empty).
Webkit needs a special placeholder text node as it can't focus empty text nodes.
This was being cleaned up too early, before the user had a chance to enter any
text.
