primal_heur.cpp: call end() on IloEnv, each round
Add valid inequality

Valid inequality f[i,j,s,t] <= v[s,t] where v[s,t] is a lower
bound on the (s,t) flow
Add simple valid inequality: f[i,j]<=c*x[i,j]{s,t}
Exclude separators and presolvers; set arc_var value in primal heuristics.
Change cplex integrality tolerance
Trying to get things working.
run.sh: fix tar command
Fix pricing with dual values for extended formulation
Remove dbg-inefficiencies from pricer and rmp
problem_mmf.h: add getters for single variables
primal_heur.cpp: do not check global bounds

Global bounds might be too strict, since they are inferred
from a subset of variables (columns). In other words, those bounds
have little meaning for the original problem.
Therefore, solutions obtained by primal heuristics need not
respect those bounds.

Similarly, one could think that propagating the global bounds in
the restricted MILP could be of some help. However, for the very
same reason explained above, one would rather *not* include those
bounds. (Although, in principle, the solution found by the current
RMILP should not violate those bounds.

Also: fix subtle bug in restricted MILP. Looping over the paths
can be incorrect when the RMILP runs after the shortest path
heuristic, since the number of paths might be larger than the
number of lambda variables actually in the problem.
Always loop on lambdas, then.
Modify the objective instead of creating a new one
Hack to repair solutions generated by <Short> heur
Fix error in variables creation under relaxation

When not using the extended formulation, lambda variables were
not correctly relaxed.
Big refactoring in main/problem/pricer/primal

Superficial changes, except for:
- better organize success/failure checks in pricer
- add SCIPfreeSol on newsol in primal, and use a copy to store
in the repair pool
Merge branch 'flow-valid-cut' of github.com:sbebo/MMF into flow-valid-cut