Mercurial: Show current branch in project tree and window title

Task-number: QTCREATORBUG-11388

Change-Id: I55c966b5026e435d0fa4d24607b7b4a3c6d9e3dc
Reviewed-by: Nikita Baryshnikov <nib952051@gmail.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/mercurial/mercurialcontrol.h

@@ -65,6 +65,7 @@ public:
     QString vcsGetRepositoryURL(const QString &directory);
     bool sccManaged(const QString &filename);
     bool vcsAnnotate(const QString &file, int line);
+    QString vcsTopic(const QString &directory);
 
 public slots:
     // To be connected to the HgTask's success signal to emit the repository/