Clean out last of PlayHandle.

gamelog/src/period.rs

@@ -1,4 +1,4 @@
-use crate::{Event, Play, PlayHandle, Team, error};
+use crate::{Event, Play, Team, error};
 use serde::Deserialize;
 
 #[derive(Debug, Deserialize, Clone)]
@@ -8,21 +8,6 @@ pub struct Period {
     pub events: Vec<Event>,
 }
 
-impl PlayHandle for Period {
-    fn plays(&self) -> Vec<Play> {
-        self.events
-            .iter()
-            .filter_map(|event| {
-                if let Event::Play(play) = event {
-                    Some(play.to_owned())
-                } else {
-                    None
-                }
-            })
-            .collect()
-    }
-}
-
 impl Period {
     pub fn team_events(
         &self,