CPTP v1.1.1

This minor version doesn't add much functionality, it's mostly about fixing and rounding edges here and there.
See changes of v1.1.0 release

New features

Partially implemented #10: VIOLATION_TOLERANCE, a constant baked at compile time, is specified independently for each cut. When the cut does not violate the constraint within the VIOLATION_TOLERANCE appreciable tolerance, it is not separated. In the future, we aim to remove this constant and make the violation tolerance more dynamic.
Closed #14: Added capacity lower bound constraint to improve the linear relaxation.
Closed #7: Implemented 2-OPT refinement for warm start solutions. After the insertion heuristic creates a valid warm start solution, it is refined using 2-OPT to try to improve it. At a first glance, it doesn't seem to achieve remarkable results.

Removed the now redundant zero_reduced_cost_threshold variable. This variable was introduced as a hack for modeling BaPCod reduced cost variables. Now from the CVRP application that we implemented in BaPCod, before generating the instances used for CPTP, we compute the duals (profits for each node) using the reduced cost variables. We then output a normal CPTP problem instance composed of euclidean distance between cities, and profits associated to each city and the depot. The zero_reduced_cost_threshold is now redundant and thus removed.
- Removed parsing of ZERO_REDUCED_COST_THRESHOLD field in VRPLIB parser src/parser.c
Introduced COST_TOLERANCE constant. A valid reduced cost tour is reported only if it is less than COST_TOLERANCE=-1e-6 which is the default constant imposed in BaPCod.
Improved handling of infeasible solutions, both from cptp executable and from the perfprof wrapper program.