Replace core language HexStrings with library entity

[Andrei Alexandrescu via Digitalmars-d]

On 3/16/15 3:02 PM, Adam D. Ruppe wrote:
> I really think users should learn the language more than the library....
> if you know the implementation of hexString, you can do so much more
> with it than if you just know the function name. (this is also a benefit
> to this kind of function over a built in, of course)

hexString just being there accessible for inspection is a good argument 
for its existence. People can use it as inspiration for their own 
abstractions. -- Andrei