Double clicking on save file doesn't automatically open the save file in the application

[backwardsEric]

The easiest ways to get this work would be to either set the HFS file type in the file's metadata (also would require changes beyond the Mac front-end since, unlike modern Angband, there isn't a file_open_hook so the front end can see when the core opens a file) or to use an extension on the names of the save files (also requiring a change to the core). Both would have to be backed by changes to the Info.plist so that the Hengband application would be recognized as handling those files.