IEnumerableExtensionMethods: add FindIndex<T>(), IndexOf<T>()
IEnumerableExtensionMethods: add FindIndex<T>(), IndexOf<T>()

- public static int FindIndex<T>(this IEnumerable<T> source, Func<T,
bool> predicate)
- public static int IndexOf<T>(this IEnumerable<T> source, T item)

TakeAsh/cs-TakeAshUtility