[MLton] mlnlffigen is awesome (was: bootstrap problem)

[Matthew Fluet]

> I completely agree that the use of MLB path variables is definitely shady.
> The whole notion of ~/.mlton/mlb-path-map being used, although very convenient
> when just doing things for oneself, is really a pain when exporting things.

Agreed.

> I would like a mlton flag which says to NOT use ~/.mlton/mlb-path-map and to
> (optionally) provide a file to use instead.  Then things which are exported
> should always use that method.

Another alternative would be to drop the implicit ~/.mlton/mlb-path-map 
and only have the flag to include a file map.  A convenient convention is 
to have ~/.mlton/mlb-path-map and when you want to use it, you point the 
flag there.