copyright year in about dialog updated

Author: DevCharly

src/main/resources/org/markdownwriterfx/messages.properties

@@ -96,7 +96,7 @@ MainWindow.helpAboutAction=About Markdown Writer FX
 
 MainWindow.about.title=About
 MainWindow.about.headerText=Markdown Writer FX
-MainWindow.about.contentText=Version {0}\nCopyright (c) 2015-2017 Karl Tauber <karl at jformdesigner dot com>\nAll rights reserved.
+MainWindow.about.contentText=Version {0}\nCopyright (c) 2015-2018 Karl Tauber <karl at jformdesigner dot com>\nAll rights reserved.
 
 MainWindow.MarkdownExtensions=Markdown Extensions