Remove redundancy in variable usage, variable qualifiers and unused variables

[badumbatish]

I'm trying to compile CXXGraph inside include/ for a private codebase and since the repo uses -Werror, -Wunused-variables and -Wignorequalifiers these errors happen.

I was wondering if theres any interest in trying to slim down these warnings directly in the library?

/Users/jjasmine/Developer/github/anon/include/CXXGraph/Edge/Edge_decl.h:60:3: error: 'const' type qualifier on return type has no effect [-Werror,-Wignored-qualifiers]
  const unsigned long long getId() const;
  ^~~~~~
In file included from /Users/jjasmine/Developer/github/anon/standalone/source/main.cpp:4:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/CXXGraph.hpp:7:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/Edge/Edge.h:25:
/Users/jjasmine/Developer/github/anon/include/CXXGraph/Edge/Edge_impl.hpp:80:1: error: 'const' type qualifier on return type has no effect [-Werror,-Wignored-qualifiers]
const unsigned long long Edge<T>::getId() const {
^~~~~~
In file included from /Users/jjasmine/Developer/github/anon/standalone/source/main.cpp:4:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/CXXGraph.hpp:11:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/Graph/Graph.h:23:
/Users/jjasmine/Developer/github/anon/include/CXXGraph/Graph/Graph_impl.hpp:460:8: error: unused variable 'undirected' [-Werror,-Wunused-variable]
  bool undirected = this->isUndirectedGraph();
       ^
In file included from /Users/jjasmine/Developer/github/anon/standalone/source/main.cpp:4:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/CXXGraph.hpp:11:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/Graph/Graph.h:31:
/Users/jjasmine/Developer/github/anon/include/CXXGraph/Graph/Algorithm/CycleDetection_impl.hpp:47:7: error: unused variable 'stateCounter' [-Werror,-Wunused-variable]
  int stateCounter = 0;
      ^
In file included from /Users/jjasmine/Developer/github/anon/standalone/source/main.cpp:4:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/CXXGraph.hpp:11:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/Graph/Graph.h:47:
/Users/jjasmine/Developer/github/anon/include/CXXGraph/Graph/IO/InputOperation_impl.hpp:32:63: error: unused parameter 'compress' [-Werror,-Wunused-parameter]
                           const std::string &OFileName, bool compress,
                                                              ^
In file included from /Users/jjasmine/Developer/github/anon/standalone/source/main.cpp:4:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/CXXGraph.hpp:11:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/Graph/Graph.h:48:
/Users/jjasmine/Developer/github/anon/include/CXXGraph/Graph/IO/OutputOperation_impl.hpp:33:62: error: unused parameter 'compress' [-Werror,-Wunused-parameter]
                          const std::string &OFileName, bool compress,
                                                             ^
In file included from /Users/jjasmine/Developer/github/anon/standalone/source/main.cpp:4:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/CXXGraph.hpp:16:
/Users/jjasmine/Developer/github/anon/include/CXXGraph/Partitioning/EdgeBalancedVertexCut.hpp:106:10: error: unused variable 'MAX_SCORE' [-Werror,-Wunused-variable]
  double MAX_SCORE = 0.0;
         ^
In file included from /Users/jjasmine/Developer/github/anon/standalone/source/main.cpp:4:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/CXXGraph.hpp:19:
/Users/jjasmine/Developer/github/anon/include/CXXGraph/Partitioning/Partition.hpp:277:16: error: unused variable 'numberOfEdges' [-Werror,-Wunused-variable]
  unsigned int numberOfEdges = 0;
               ^
/Users/jjasmine/Developer/github/anon/include/CXXGraph/Partitioning/Partition.hpp:292:16: error: unused variable 'numberOfNodes' [-Werror,-Wunused-variable]
  unsigned int numberOfNodes = 0;
               ^
In file included from /Users/jjasmine/Developer/github/anon/standalone/source/main.cpp:4:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/CXXGraph.hpp:23:
In file included from /Users/jjasmine/Developer/github/anon/include/CXXGraph/Partitioning/Partitioner.hpp:39:
/Users/jjasmine/Developer/github/anon/include/CXXGraph/Partitioning/WeightBalancedLibra.hpp:140:14: error: unused variable 's_node' [-Werror,-Wunused-variable]
      size_t s_node = (u_degree > v_degree) ? v : u;
             ^
/Users/jjasmine/Developer/github/anon/include/CXXGraph/Partitioning/WeightBalancedLibra.hpp:141:14: error: unused variable 't_node' [-Werror,-Wunused-variable]
      size_t t_node = (u_degree > v_degree) ? u : v;
             ^
11 errors generated.
make[2]: *** [standalone/CMakeFiles/anonStandalone.dir/source/main.cpp.o] Error 1
make[1]: *** [standalone/CMakeFiles/anonStandalone.dir/all] Error 2