scene: stagedirection: switch to a generic playlist name based interface to mixxx, instead of PWM episode numbers

src/scene/mod.rs

@@ -7,7 +7,7 @@ pub mod conversation;
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
 pub struct StageDirection {
-    pub episode_number: u32,
+    pub playlist: String,
     #[serde(skip)]
     #[serde(default="StageDirection::default_end_time")]
     pub end_time: DateTime<Utc>,
@@ -27,7 +27,7 @@ impl StageDirection {
 impl Default for StageDirection {
     fn default() -> Self {
         Self {
-            episode_number: 0,
+            playlist: Default::default(),
             end_time: Self::default_end_time(),
             narrative: Default::default(),
         }