the action buttons have a value that matches up with the key for the
target form in the `this.states` object - we can just set the
currentState to that and call re-render and it all Just Works™.
detatch and reattach feel better than hide/unhide, mainly because it
means when the form is posted, any data that might linger in them
definitely won't be sent in the POST.
if action buttons are shown (either the nothing selected actions or the
stuff selected actions), when a checkbox is selected or deselected,
count how many checkboxes are selected. If it's zero, then show the
new template/folder buttons, if it's non-zero, then show the move
options.
Under the hood, we set the `currentState` variable, then the render fn
shows that element and hides all others.
have a bunch of separate elements within the sticky_template_forms div
that we hide or show based on button presses and such. This commit just
sets up the class - it doesn't actually deal with button presses or
checkboxes etc yet.
