An experimental LPSolverWrapper class which uses glpk. For a short
demo, max flow problems are solved with it. This demo does not
demonstrates, but the main aims of this class are row and column
generation capabilities, i.e. to be a core for easily
implementable branch-and-cut a column generetion algorithms.

 p max 2 1

 n 1 s

 n 2 t

 a 1 2 5