public IEnumerable<DubBuildSettings> GetBuildSettings(ConfigurationSelector sel)
{
yield return CommonBuildSettings;
DubProjectConfiguration pcfg;
if (sel == null || (pcfg = GetConfiguration(sel) as DubProjectConfiguration) == null)
foreach (DubProjectConfiguration cfg in Configurations)
yield return cfg.BuildSettings;
else
yield return pcfg.BuildSettings;
}