[Qt] add utilitydialog.cpp/h and helpmessage class

- adds a nice and well formated dialog, which displays our -? help message
  (all options/paramaters)
- moves aboutdialog.cpp/h to the new utilitydialog
- move GUI shutdown window to utilitydialog

src/qt/guiutil.cpp

@@ -591,47 +591,6 @@ void restoreWindowGeometry(const QString& strSetting, const QSize& defaultSize,
     parent->move(pos);
 }
 
-HelpMessageBox::HelpMessageBox(QWidget *parent) :
-    QMessageBox(parent)
-{
-    header = tr("Bitcoin Core") + " " + tr("version") + " " +
-        QString::fromStdString(FormatFullVersion()) + "\n\n" +
-        tr("Usage:") + "\n" +
-        "  bitcoin-qt [" + tr("command-line options") + "]                     " + "\n";
-
-    coreOptions = QString::fromStdString(HelpMessage(HMM_BITCOIN_QT));
-
-    uiOptions = tr("UI options") + ":\n" +
-        "  -lang=<lang>           " + tr("Set language, for example \"de_DE\" (default: system locale)") + "\n" +
-        "  -min                   " + tr("Start minimized") + "\n" +
-        "  -splash                " + tr("Show splash screen on startup (default: 1)") + "\n" +
-        "  -choosedatadir         " + tr("Choose data directory on startup (default: 0)") + "\n";
-
-    setWindowTitle(tr("Bitcoin Core"));
-    setTextFormat(Qt::PlainText);
-    // setMinimumWidth is ignored for QMessageBox so put in non-breaking spaces to make it wider.
-    setText(header + QString(QChar(0x2003)).repeated(50));
-    setDetailedText(coreOptions + "\n" + uiOptions);
-}
-
-void HelpMessageBox::printToConsole()
-{
-    // On other operating systems, the expected action is to print the message to the console.
-    QString strUsage = header + "\n" + coreOptions + "\n" + uiOptions;
-    fprintf(stdout, "%s", strUsage.toStdString().c_str());
-}
-
-void HelpMessageBox::showOrPrint()
-{
-#if defined(WIN32)
-        // On Windows, show a message box, as there is no stderr/stdout in windowed applications
-        exec();
-#else
-        // On other operating systems, print help text to console
-        printToConsole();
-#endif
-}
-
 void setClipboard(const QString& str)
 {
     QApplication::clipboard()->setText(str, QClipboard::Clipboard);