String.splitLines

[Charles]

I discovered that Python has a .splitLines method on String which I think is quite convenient as there are multiple line ending conventions. Via this method, you don't have to think about them as much because it works with any of them.

I added an extension method on System.String along with unit test cases. I also updated the StandardLibraryExtensionMethods wiki page with this and some other String conveniences that were already in place.