Fix $tw.utils.hasClass() to work even if the element doesn't have a className property
Improve popup dismissal

Now we ignore clicks if they come from an element that has an ancestor
with the class `tw-popup`
Update the reveal widget to set the tw-popup class
Update the tiddler info panel to use the new tw-popup class

This fixes the problem with the inability to click on items within the
tiddler info panel (including the static URL)