Minor enhancements.

src/auxiliaries/attachment_helper.cpp

 /*
- * Copyright (C) 2014-2017 CZ.NIC
+ * Copyright (C) 2014-2018 CZ.NIC
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -47,9 +47,9 @@ QString getApproximatelyAttachmentFileSizeFromBase64(int base64Length)
 	return str;
 }
 
-QString getAttachmentFileIconFromFileExtension(QString fileName)
+QString getAttachmentFileIconFromFileExtension(const QString &fileName)
 {
-	QString img = "qrc:/fileicons/fileicon_blank.png";
+	QString img("qrc:/fileicons/fileicon_blank.png");
 	QFileInfo fi(fileName);
 	const QString ext = fi.suffix();
 	ext.toLower();

src/auxiliaries/attachment_helper.h

 /*
- * Copyright (C) 2014-2017 CZ.NIC
+ * Copyright (C) 2014-2018 CZ.NIC
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -40,6 +40,6 @@ QString getApproximatelyAttachmentFileSizeFromBase64(int base64Length);
  * @param[in] fileName Attachment filename with extension.
  * @return Attachment icon filename string.
  */
-QString getAttachmentFileIconFromFileExtension(QString fileName);
+QString getAttachmentFileIconFromFileExtension(const QString &fileName);
 
 #endif /* _ATTACHMENT_HELPER_H_ */

src/setwrapper.h

@@ -41,7 +41,7 @@ public:
 	/*!
 	 * @brief Constructor.
 	 */
-	GlobalSettingsQmlWrapper(QObject *parent = Q_NULLPTR);
+	explicit GlobalSettingsQmlWrapper(QObject *parent = Q_NULLPTR);
 
 	/*!
 	 * @brief Get application version string.