[MLton] extending the cml library

[Matthew Fluet]

> > I am extending the cml library in MLton for my research. I would like to 
> > use all the mlton libraries in my code, mainly directedgraph.  In the 
> > core-cml.mlb I added ../../mlton/sources.mlb, but this clearly is not 
> > correct because when I do a make libraries it is complaining the file is 
> > not found in build/lib/sml/ etc etc.

P.S.  Remember that neither the Basis Library nor the MLton Libraries are
thread-safe or CML aware.  Be very careful using a DirectedGraph.t value
in two threads, as a DG.t is an imperative data-structure.  Property lists
are used extensively in the DirectedGraph module; there are clear race
conditions in updating the property list statistics, but that won't change
their behavior.