CollectionView#filter accepts a callback which might override the default filtering behavior (hiding the view). But insertView doesn’t use this callback, it directly hides it:
# Hide the view if it’s filtered
$viewEl.css 'display', 'none'
So the whole idea is sabotaged…
Background: We’re using filtering for just marking an element with an enable/disable class. At the moment we have to override insertView.
The filter callback could be a normal method like filterer, then it can be used automatically in insertView, just like filterer is used. There’s no need to call @filter() explicitly at the moment, declaring a filterer method is enough. Same should apply for the filter callback.
Add `CollectionView#filterCallback`. Closes gh-210.