welcome screen: preview in news feed, Buttons added, resizing sanatized

Manage Sessions replaces "Restore last session" (which can be done by clicking
the "(last session)" session anyway. Also, added a "Create New Project" button.
Ensured that the welcome screen is only as high as needed (will orient on the
amount of items in the contained treewidgets). Scrolling is still last resort.

src/plugins/coreplugin/rssfetcher.h

@@ -44,7 +44,7 @@ public:
     RSSFetcher(int maxItems, QObject *parent = 0);
 
 signals:
-    void newsItemReady(const QString& title, const QString& url);
+    void newsItemReady(const QString& title, const QString& desciption, const QString& url);
 
 public slots:
     void fetch(const QUrl &url);
@@ -60,6 +60,7 @@ private:
     QXmlStreamReader m_xml;
     QString m_currentTag;
     QString m_linkString;
+    QString m_descriptionString;
     QString m_titleString;
 
     QHttp m_http;