Wrapper around String

[sideeffffect]

add Functional wrappers around String instance methods

[forki]

cool

[smoothdeveloper]

I know this is old PR, but this kind of modules need to be in other namespace than root.

the library states: Functions to make C# - F# interop easier.

Whenever a C# code has using FSharpx; as well as using System it will break usage of String being ambiguous, same for Enum.