add drag and drop onto app icon (dock etc.) support for MacOS platform.

common/pdf_comic.h

@@ -0,0 +1,22 @@
+#ifndef PDF_COMIC_H
+#define PDF_COMIC_H
+
+#include <QObject>
+#include <QImage>
+
+class MacOSXPDFComic
+{
+public:
+    MacOSXPDFComic();
+    ~MacOSXPDFComic();
+    bool openComic(const QString & path);
+    void closeComic();
+    unsigned int numPages();
+    QImage getPage(const int page);
+    void releaseLastPageData();
+private:
+    void * document;
+    void * lastPageData;
+};
+
+#endif // PDF_COMIC_H