Deal + Hand

Todo: a simplified version of the .GroupBy() extension

• System.Linq.IQueryable<Hand<TKey,TElement>> Deal<TSource,TKey,TElement> (this System.Linq.IQueryable<TSource> source, int maxCountEach, System.Linq.Expressions.Expression<Func<TSource,TKey>> keySelector)
• class Hand<TKey,TElement>