OS X: Fix a few memory leaks.

src/game/boe.menus.mac.mm

@@ -40,13 +40,13 @@ MenuHandle actions_menu,music_menu,mage_spells_menu,priest_spells_menu;
 
 @interface MonsterWrapper : NSObject
 @property cMonster* monst;
-+(id) withMonster: (cMonster&) theMonster;
++(id) withMonster: (cMonster&) theMonster NS_RETURNS_RETAINED;
 @end
 
 @interface SpellWrapper : NSObject
 @property int num;
 @property eSkill type;
-+(id) withSpell:(int) num ofType:(eSkill) type;
++(id) withSpell:(int) num ofType:(eSkill) type NS_RETURNS_RETAINED;
 @end
 
 void hideMenuBar() {
@@ -301,7 +301,7 @@ void menu_activate() {
 +(id) withMonster:(cMonster&) theMonster {
 	MonsterWrapper* wrapper = [[MonsterWrapper alloc] init];
 	[wrapper setMonst: &theMonster];
-	return [wrapper retain];
+	return wrapper;
 }
 @end
 
@@ -312,7 +312,7 @@ void menu_activate() {
 	SpellWrapper* wrapper = [[SpellWrapper alloc] init];
 	[wrapper setType: type];
 	[wrapper setNum: num];
-	return [wrapper retain];
+	return wrapper;
 }
 @end