macosx: re-implement 'video-deco' support (close #6426)

disabling this option will get you a separate video output window without any visible playback controls or window border. resizing is supported through hotkeys and Lion's native mechanism if available. Control the playback through menu and main window controller. Note that 'embedded' is obviously ignored in this mode.
(cherry picked from commit f01f7eca64bd6f007afeaaeed623990e76a43de8)

modules/gui/macosx/MainWindow.h

@@ -93,6 +93,7 @@
     BOOL b_dropzone_active;
     BOOL b_splitview_removed;
     BOOL b_minimized_view;
+    BOOL b_video_deco;
     int i_lastSplitViewHeight;
     int i_lastShownVolume;
     input_state_e cachedInputState;
@@ -204,6 +205,7 @@
 @interface VLCDetachedVideoWindow : NSWindow
 {
     BOOL b_dark_interface;
+    BOOL b_video_deco;
     NSRect previousSavedFrame;
 }