added alpha channel

src/config.rs

@@ -0,0 +1,20 @@
+#[derive(Default, Clone, Copy)]
+pub struct Config {
+    pub rendering_mode: RenderingMode,
+}
+
+#[derive(Clone, Copy)]
+pub enum RenderingMode {
+    /// only 16 colors by accessed by name, no alpha support
+    BaseColors,
+    /// 8 bit colors, will be downsampled from rgb colors
+    Ansi,
+    /// 24 bit colors, most terminals support this
+    Rgb,
+}
+
+impl Default for RenderingMode {
+    fn default() -> Self {
+        RenderingMode::Rgb
+    }
+}