AbstractActionExecutor.isAvailable() method will be changed to take the
availability.multiple property into account in the availability evaluation (ATM it just returns false if the
items.length is bigger than 1). Note (for the documentation): if more advanced availability evaluation is required (e.g. action should be available only if all the items are on the same level, or have the same parent), the Availability Rules should be used.
BrowserPresenter.executeAction() method will be changed to pass the whole item list to the
actionExecutor in such case, instead of just the first selected item. (There is already a TODO note with the above issue ID.)