Add hidden configuration for showing the document title (if any) in the title...

Add hidden configuration for showing the document title (if any) in the title bar. Default is true (as before).
Based on a patch by Alejandro Exojo, thanks!
$ kwriteconfig --file okularpartrc --group General --key DisplayDocumentTitle --type bool false

BUG: 158401

svn path=/trunk/KDE/kdegraphics/okular/; revision=890576

conf/okular.kcfg

@@ -156,6 +156,9 @@
   <entry key="ShowOSD" type="Bool" >
    <default>true</default>
   </entry>
+  <entry key="DisplayDocumentTitle" type="Bool" >
+   <default>true</default>
+  </entry>
   <entry key="UseKTTSD" type="Bool" />
   <entry key="WatchFile" type="Bool" >
    <default>true</default>

part.cpp

@@ -703,16 +703,20 @@ void Part::loadCancelled(const QString &reason)
 
 void Part::setWindowTitleFromDocument()
 {
-    // if the document have a 'DocumentTitle' flag set (and it is not empty), set it as title
-    QString title = m_document->metaData( "DocumentTitle" ).toString();
-    if ( !title.isEmpty() && !title.trimmed().isEmpty() )
-    {
-        emit setWindowCaption( title );
-    }
-    else
+    // If 'DocumentTitle' should be used, check if the document has one. If
+    // either case is false, use the file name.
+    QString title = realUrl().fileName();
+
+    if ( Okular::Settings::displayDocumentTitle() )
     {
-        emit setWindowCaption( realUrl().fileName() );
+        const QString docTitle = m_document->metaData( "DocumentTitle" ).toString();
+        if ( !docTitle.isEmpty() && !docTitle.trimmed().isEmpty() )
+        {
+             title = docTitle;
+        }
     }
+
+    emit setWindowCaption( title );
 }
 
 void Part::slotGeneratorPreferences( )