Clean up some class inheritance issues in feeds

lib/AtomFeed.php

@@ -1,4 +1,5 @@
 <?
+use Safe\DateTime;
 use function Safe\file_get_contents;
 use function Safe\file_put_contents;
 use function Safe\preg_replace;
@@ -28,6 +29,15 @@ class AtomFeed extends Feed{
 		return $this->XmlString;
 	}
 
+	public function SaveIfChanged(): void{
+		// Did we actually update the feed? If so, write to file and update the index
+		if($this->HasChanged($this->Path)){
+			// Files don't match, save the file
+			$this->Updated = new DateTime();
+			$this->Save();
+		}
+	}
+
 	protected function HasChanged(string $path): bool{
 		if(!is_file($path)){
 			return true;

lib/Feed.php

@@ -40,15 +40,6 @@ class Feed{
 		return '';
 	}
 
-	public function SaveIfChanged(): void{
-		// Did we actually update the feed? If so, write to file and update the index
-		if($this->HasChanged($this->Path)){
-			// Files don't match, save the file
-			$this->Updated = new DateTime();
-			$this->Save();
-		}
-	}
-
 	public function Save(): void{
 		$feed = $this->GetXmlString();
 

lib/RssFeed.php

@@ -23,6 +23,14 @@ class RssFeed extends Feed{
 		return $this->XmlString;
 	}
 
+	public function SaveIfChanged(): void{
+		// Did we actually update the feed? If so, write to file and update the index
+		if($this->HasChanged($this->Path)){
+			// Files don't match, save the file
+			$this->Save();
+		}
+	}
+
 	protected function HasChanged(string $path): bool{
 		// RSS doesn't have information about when an item was updated,
 		// only when it was first published. So, we approximate on whether the feed