ResourcePreviewer: save and restore default settings of InstrumentTrack

After instantiation of InstrumentTrack save its settings so we can
restore it each time before previewing resources. Otherwise preview
of incomplete presets or just samples could be distorted by settings
of previosly loaded preset.

Signed-off-by: Tobias Doerffel <tobias.doerffel@gmail.com>

include/ResourcePreviewer.h

@@ -27,6 +27,7 @@
 #define _RESOURCE_PREVIEWER_H
 
 #include "track_container.h"
+#include "mmp.h"
 
 class Piano;
 class ResourceItem;
@@ -57,6 +58,8 @@ private:
 	PreviewTrackContainer m_previewTrackContainer;
 	instrumentTrack * m_previewTrack;
 
+	multimediaProject m_defaultSettings;
+
 } ;