Fixes:
* do not strip 'filter' as a directory prefix.
* proper spacing for scaled sheet fonts.
* fix of transparent color in BMF fonts.
* fix restart button on error pane in Windows.
* do not skip over empty 'if's with a condition that would error out.
The same logic as in GZDoom applies: The root must not have any other content and the subdirectory must contain identifiable game content.
Some handling was also added to strip out macOS resource fork folders because they can contain data that can confuse file detection.
Unfortunately necessary because Ion Fury savegames store 120 GB(!!) of data, mostly zeros.
Unlike the old method, this compresses the entire savegame as one block using a ZLib stream so it should be a lot more efficient now.
