Conversation code cleaned up a lot.

include/dawn/display/animation/timeline.h

@@ -26,6 +26,9 @@ typedef void timelinecallback_t(timeline_t *timeline, timelineaction_t *action,
 );
 
 typedef struct _timelineaction_t {
+  /** Pointer to any custom user data the timeline action wants to use. */
+  void *data;
+
   /**
    * The time that this action should occur within the timeline
    * set to 0 or less to start immediately.
@@ -50,7 +53,9 @@ typedef struct _timelineaction_t {
   bool loop;
 
   timelinecallback_t *onStart;
+  
   timelinecallback_t *onDuration;
+
   timelinecallback_t *onEnd;
 } timelineaction_t;