Add string removal

CMakeLists.txt

src/input/pdptw_data.cpp

src/input/pdptw_data.h

src/lns/modification/pair/remove_pair.cpp

src/lns/operators/destruction/random_destroy.cpp

src/lns/operators/destruction/string_removal.cpp

src/lns/operators/destruction/string_removal.h

...operators/reconstruction/list_heuristic_cost_oriented.cpp

src/lns/solution/route.cpp

src/lns/solution/route.h

src/lns/solution/solution.cpp

src/lns/solution/solution.h

src/mains/main.cpp