Fix mini-player ghosting, and allow in full screen apps (fixes #79, f…

…ixes #309)

Such a simple fix for #79 that I can't even believe it took this long
-- in fact, I remember trying to investigate this issue and learning
that it was simply not possible without creating a UI agent
application. But apparently, adding
`NSWindowCollectionBehaviorFullScreenAuxiliary` does the trick.

The issue in #309 is that when switching spaces at any point after the
mini player has been opened and closed, a "ghost" of the mini player
will appear on the space being switched to, and disappears once the
space is fully switched. Changing to
`NSWindowCollectionBehaviorMoveToActiveSpace` means that the mini
player does not appear on all spaces, it simply just opens in the space
in which it is activated, which is almost the same use case.

radiant-player-mac/Popup/PopupPanel.m

@@ -29,7 +29,7 @@ -(void)awakeFromNib
     [self setBackgroundColor:[NSColor clearColor]];
     [self setOpaque:NO];
     [self setLevel:NSPopUpMenuWindowLevel];
-    [self setCollectionBehavior:NSWindowCollectionBehaviorCanJoinAllSpaces|NSWindowCollectionBehaviorTransient];
+    [self setCollectionBehavior:NSWindowCollectionBehaviorMoveToActiveSpace|NSWindowCollectionBehaviorTransient|NSWindowCollectionBehaviorFullScreenAuxiliary];
     [self setFloatingPanel:self.isAlwaysOnTop];
     [self setHidesOnDeactivate:NO];
     [self setDelegate:self];