added enum for change-slide handling

src/modules/stream_states/enums.rs

@@ -45,3 +45,18 @@ impl Scenes {
     }
 }
 
+#[derive(PartialEq, Debug, Clone, Copy)]
+pub enum SlideChange {
+    Next,
+    Previous,
+}
+
+impl SlideChange {
+    pub fn to_string(&self) -> String {
+        match self {
+            SlideChange::Next => {String::from_str("Next_Slide").unwrap()},
+            SlideChange::Previous => {String::from_str("Prev_Slide").unwrap()},
+        }
+    }
+}
+