CppTools: Add revisions to AbstractEditorSupport

So far revisions for AbstractEditorSupport were not needed because until
recently we only had a single snapshot ("global snapshot"). Now, since
editor snapshots are introduced, we need to make sure to update the
corresponding documents in these snapshots, too. To do this efficiently,
a revision is introduced for AbstractEditorSupport.

Task-number: QTCREATORBUG-10894

Change-Id: Ibad1dbbafb7c721d1328959c1e903345fe465326
Reviewed-by: Christian Stenger <christian.stenger@digia.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cpptools/abstracteditorsupport.h

@@ -50,6 +50,7 @@ public:
     virtual QString fileName() const = 0;
 
     void updateDocument();
+    unsigned revision() const { return m_revision; }
 
     // TODO: find a better place for common utility functions
     static QString functionAt(const CppModelManagerInterface *mm,
@@ -60,6 +61,7 @@ public:
 
 private:
     CppModelManagerInterface *m_modelmanager;
+    unsigned m_revision;
 };
 
 } // namespace CppTools