When setting splitter's output priority, initialize to whichever side the user opened the splitter's options menu

[jasongraph]

Currently, if you click on the output priority box in a splitter's menu or set a filter on a splitter, it will always initialize to the output priority to the left, which sometimes requires an awkward additional click to set output priority to the other side.


Suppose the game instead remembered if you opened the splitter's options gui by clicking on the right side or left side of the splitter. Then when you click on the splitter's output priority checkbox or set an item filter, it would set the output priority on the corresponding right or left side you clicked on earlier.


This could make it simpler to setup filtered splitters in general, though it could be confusing to existing players who have gotten used to it always initializing to left.