Jalal

This adds `DescriptionAttribute` over `enum` types as described in #602

Hello EPPlus doesn't consider `DescriptionAttribute` when extracting `enum` values. For example: ```csharp using OfficeOpenXml; using OfficeOpenXml.Table; using System; using System.Collections.Generic; using System.ComponentModel; using System.IO; namespace EPPlusEnum { class Program {...