Don't pushState until drag selection completes #55
Description
Currently each line dragged over will make a history entry, which is neat that it works properly, but ideally a drag selection would count as a single history entry to reduce spam.
Can probably be done with a flag set by the drag logic? Not sure how to do it cleanly while keeping the diff view logic separated the from the viewer - but at this point that distinction is kind of pointless. Maybe some general cleanup can be done if that's removed or refactored in some way.
Or can just have some "optimistic" selection state for rendering only local to the patch view.