Denoting the product category as required

Using common style: span.required *
Filter deleted products in products report

BugHerd 484: Remove deleted products from Product / Inventory reports
Navigation Callbacks (confirmation to leave) refs

A navigation callback could give only a fixed value at load time. Now it
can act depending on the site's state just before the page is unloaded.
Navigation Callbacks for WebKit
Unify nav-check and nav-callback attributes in nav-check-callback

The value of nav-check was not used and nav-callback was only important
if nav-check was given. So we need only one attribute, now named
nav-check-callback.
Leave-page-warning only after changing inputs

The enterprise form is now set 'dirty' whenever an input changes. The
navigation callback confirms to leave the page only if the form is
dirty.
Use scope
Merge branch 'product-reports-without-deleted'
Merge branch 'product-category-required'
Merge branch 'enterprise-form-confirmation'