Stream output: fix longstanding compilation warnings

Sources/VLCStreamOutput.m

@@ -34,6 +34,12 @@
 @end
 
 @implementation VLCStreamOutput
+
+- (instancetype)init
+{
+    return [self initWithOptionDictionary:nil];
+}
+
 - (instancetype)initWithOptionDictionary:(NSDictionary *)dictionary
 {
     if (self = [super init])

Sources/VLCStreamSession.m

@@ -66,7 +66,7 @@
     [super stop];
 }
 
-- (BOOL)play
+- (void)play
 {
     NSString * libvlcArgs;
     if( self.drawable )
@@ -85,7 +85,6 @@
         [super setMedia: self.media];
     }
     [super play];
-    return YES;
 }
 
 + (NSSet *)keyPathsForValuesAffectingDescription