Core: Add some helper methods to VcsManager

Make VcsManager provide a generic way to list all IVersionControls
and to search for a specific one based on its id.

At some point we want to register the IVersionControls directly
with the VcsManager instead of going through the object pool and this
is a first step into this direction.

Change-Id: Id4ded85b29487f6d8adcd0cec1de490afae07132
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/plugins/coreplugin/vcsmanager.h

@@ -32,6 +32,7 @@
 #define VCSMANAGER_H
 
 #include "core_global.h"
+#include "id.h"
 
 #include <QString>
 #include <QObject>
@@ -63,6 +64,9 @@ public:
 
     static void extensionsInitialized();
 
+    static QList<IVersionControl *> versionControls();
+    static IVersionControl *versionControl(Id id);
+
     static void resetVersionControlForDirectory(const QString &inputDirectory);
     static IVersionControl *findVersionControlForDirectory(const QString &directory,
                                                            QString *topLevelDirectory = 0);