public ProjectSnapshot NewSnapshot(string projFullPath)
        {
            ProjectSnapshot ps = GetSnapshot(projFullPath);
            if (ps != null)
            {
                return ps;
            }

            string saveFile = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments),
                @"AutoProjectFiles\Snapshots\" + Guid.NewGuid().ToString() + ".xml");
            ps = new ProjectSnapshot(saveFile);
            ps.ProjectFile = projFullPath;
            ps.Save();
            Snapshots().Add(ps);
            return ps;
        }