Version control: Replace per-VCS output panes with a single one.

...and give it some color and formatting.

src/plugins/git/gitclient.h

@@ -145,10 +145,6 @@ public:
 public slots:
     void show(const QString &source, const QString &id);
 
-private slots:
-    void appendAndPopup(const QString &text);
-    void appendDataAndPopup(const QByteArray &data);
-
 private:
     VCSBase::VCSBaseEditor *createVCSEditor(const QString &kind,
                                                  QString title,