[MLton] unicode

[Matthew Fluet]

> Neither is there real support for Unicode in the Standard ML Basis Library. 
> The general consensus (which includes the opinions of the editors of the 
> Basis Library) is that the LargeChar structure is insufficient for the 
> purposes of Unicode.

Sorry, minor mistake in the above:  The "WideChar" structure is 
insufficient for the purposes of Unicode.  There is no "LargeChar" 
structure, which in itself is a deficiency, since a programmer may not 
program against the largest supported character size.