[opam-devel] Documentation for the external solver preference language

[Roberto Di Cosmo]

There is now detailed documentation on how to use the preference 
language supported by CUDF-compliant external solver, and most
notably by aspcud:
 
 * general discussion: http://www.dicosmo.org/MyOpinions/index.php/2014/03/05/137-user-preferences-for-dependency-solvers-a-short-survey-and-new-features-added-in-the-latest-aspcud-solver

 * opam-specific version of the above: http://opam.ocaml.org/doc/Specifying_Solver_Preferences.html

-- 
Roberto