Issue #22: Fix compilation warnings

PdfTool/pdftoolabstractapplication.h

@@ -44,12 +44,20 @@ struct PDFToolTranslationContext
 
 struct PDFToolOptions
 {
+    enum DateFormat
+    {
+        LocaleShortDate,
+        LocaleLongDate,
+        ISODate,
+        RFC2822Date
+    };
+
     // For option 'ConsoleFormat'
     PDFOutputFormatter::Style outputStyle = PDFOutputFormatter::Style::Text;
     QString outputCodec = "UTF-8";
 
     // For option 'DateFormat'
-    Qt::DateFormat outputDateFormat = Qt::DefaultLocaleShortDate;
+    DateFormat outputDateFormat = LocaleShortDate;
 
     // For option 'OpenDocument'
     QString document;
@@ -252,6 +260,8 @@ public:
     void initializeCommandLineParser(QCommandLineParser* parser) const;
     PDFToolOptions getOptions(QCommandLineParser* parser) const;
 
+    static QString convertDateTimeToString(const QDateTime& dateTime, PDFToolOptions::DateFormat dateFormat);
+
 protected:
     /// Tries to read the document. If document is successfully read, true is returned,
     /// if error occurs, then false is returned. Optionally, original document content