png file support

src/palette.rs

@@ -36,6 +36,7 @@ impl Palette {
             "gpl"  => Self::from_gpl(path),
             "hex"  => Self::from_hex(path),
             "pal"  => Self::from_jasc(path),
+            "png"  => Self::from_png(path),
             "txt"  => Self::from_txt(path),
             "toml" => Self::from(
                 path.file_stem().as_ref().unwrap().to_str().unwrap(),