Rummage

- **FIX**: Support info won't open.
- **FIX**: Small internal code improvements.

- **FIX**: Linux regression of date time control color due to recent color fix for macOS in 4.15.1.

- **NEW**: Require `backrefs` 5.0+ which provides significant Unicode improvements and bug fixes when paired with Re. One notable change is that Unicode properties now respect the Unicode Properties flags and Unicode properties will be limited to the ASCII range when not enabled just like Regex does. Also POSIX style patterns have been expanded to handle any Unicode property, POSIX and otherwise. Check out [Backrefs' documentation][backrefs] for more information. Also, the deprecated search references (`\l`, `\L`, `\c`, and `\C`) are no longer available, though you can always use the other forms of `[[:lower:]]`, `\p{lower}`, etc.
- **NEW**: Require new `wcmatch` 8.0.1+.
- **FIX**: Remove old `gntp` from support info dialog as we no longer use that package.

- **FIX**: High Sierra and below don't work the same in regard to colors. Add special logic to skip dynamic color in old macOS versions as they will result in black UI controls.

- **NEW**: Formally support Python 3.9.
- **NEW**: Formally drop Python 3.5.
- **NEW**: Use Apple's Big Sur template for the macOS dock icon.