cleanup

src/board.rs

@@ -68,7 +68,7 @@ impl Board {
     }
 
     pub fn what_if(&self, i: usize, j: usize, piece: Piece) -> Option<(Self, usize)> {
-        let mut self_copy = self.clone();
+        let mut self_copy = *self;
         if self_copy.get(i, j).is_some() {
             return None;
         }
@@ -85,7 +85,7 @@ impl Board {
                 return Ok(());
             }
         }
-        Err(format!("move would not propegate"))
+        Err("move would not propegate".to_string())
     }
 
     /// Propegate piece captures originating from (i, j)