add utf8-string in haskell platform

[Don Stewart]

paolo.losi:
> Bryan O'Sullivan wrote:
>> but we shouldn't be using String for text manipulation, and bundling 
>> utf8-string implicitly blesses that approach. 
>
> ... sorry for the naive question. If we should not be using String,
> what should we be using instead?

    For *text manipulation* (i.e. large bodies of text) a packed
    representation supporting unicode is appropriate. The 'text' package
    is the main candidate here.