Replace core language HexStrings with library entity

[Andrei Alexandrescu via Digitalmars-d]

On 3/15/15 2:37 PM, Walter Bright wrote:
> On 3/15/2015 1:38 PM, "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm at gmx.net>"
> wrote:
>> Can we make it so it returns a ubyte[]?
>
> Unfortunately, it needs to be a dropin replacement for x"...", which
> returns a string/wstring/dstring.

That's what nice about library artifacts vs. language artifacts: you can 
add more of the former! Define hexBytes and hexString. -- Andrei