Display release date in about dialog.

doc/changelog.txt

@@ -10,6 +10,8 @@ Changes:
   user.
 - gui: While checking, show new URLs added in the URL list view by
   scrolling down.
+- gui: Display release date in about dialog.
+  Closes: SF bug #3297255
 
 Features:
 - gui: Add syntax highlighting for Qt editor in case QScintilla

linkcheck/configuration/__init__.py

@@ -32,6 +32,7 @@ from . import confparse
 from ..decorators import memoized
 
 Version = configdata.version
+ReleaseDate = configdata.release_date
 AppName = configdata.appname
 App = AppName+u" "+Version
 Author = configdata.author

linkcheck/gui/__init__.py

@@ -256,10 +256,12 @@ class LinkCheckerMain (QtGui.QMainWindow, Ui_MainWindow):
             "donateurl": configuration.DonateUrl,
             "pyver": u"%d.%d.%d" % sys.version_info[:3],
             "modules": modules,
+            "releasedate": configuration.ReleaseDate,
         }
         QtGui.QMessageBox.about(self, _(u"About %(appname)s") % d,
             _(u"""<qt><center>
 <h1>%(app)s</h1>
+<p>Released on %(releasedate)s
 <p>Python: %(pyver)s<br>
 %(modules)s
 <p>%(copyright)s