/// <summary>
/// constructor optionally calls method to init the column information structure
/// and return the itself - singleton
/// </summary>
/// <param name="dt">table</param>
/// <param name="init">if true, initialize; for example, on import</param>
/// <returns></returns>
public static dtColumnInformation getdtCI(DataTable dt, bool init)
{
//pass null after initialization to access the DTcolInfo property
//or pass init=true (after import) to initialize
if (dtCI == null || init) dtCI = new dtColumnInformation(dt);
return dtCI;
}