Add virtual destructors to base classes

src/actions.h

@@ -189,7 +189,9 @@ extern size_t FooterStartY;
 struct BaseAction
 {
 	BaseAction(Type type_, const char *name_): m_name(name_), m_type(type_) { }
-	
+
+	virtual ~BaseAction() { }
+
 	const std::string &name() const { return m_name; }
 	Type type() const { return m_type; }
 	

src/lyrics_fetcher.h

@@ -29,7 +29,9 @@
 struct LyricsFetcher
 {
 	typedef std::pair<bool, std::string> Result;
-	
+
+	virtual ~LyricsFetcher() { }
+
 	virtual const char *name() const = 0;
 	virtual Result fetch(const std::string &artist, const std::string &title);