fix new warnings and escape apply namespace

- `std::apply` is part of C++17 and the compiler wants to use it because
of ADL. Thus it is now necessary to escape it as `::apply`.
- remove some `using namespace std` remaining in the sources.
- fix simple warnings.

eo/tutorial/Lesson1/FirstBitGA.cpp

@@ -38,7 +38,7 @@ double binary_value(const Indi & _indi)
 }
 // GENERAL
 //-----------------------------------------------------------------------------
-void main_function(int argc, char **argv)
+void main_function(int /*argc*/, char **/*argv*/)
 {
 // PARAMETRES
   // all parameters are hard-coded!

eo/tutorial/Lesson1/FirstRealGA.cpp

@@ -38,7 +38,7 @@ double real_value(const Indi & _indi)
 }
 // GENERAL
 //-----------------------------------------------------------------------------
-void main_function(int argc, char **argv)
+void main_function(int /*argc*/, char **/*argv*/)
 {
 // PARAMETRES
   // all parameters are hard-coded!

eo/tutorial/Lesson1/exercise1.3.cpp

@@ -39,7 +39,7 @@ double binary_value(const Indi & _indi)
 
 //-----------------------------------------------------------------------------
 
-void main_function(int argc, char **argv)
+void main_function(int /*argc*/, char **/*argv*/)
 {
   const unsigned int SEED = 42;	// seed for random number generator
   const unsigned int VEC_SIZE = 8; // Number of bits in genotypes

eo/tutorial/Lesson2/FirstRealEA.cpp

@@ -36,7 +36,7 @@ using namespace std;
 // GENERAL
 //-----------------------------------------------------------------------------
 
-void main_function(int argc, char **argv)
+void main_function(int /*argc*/, char **/*argv*/)
 {
 // PARAMETRES
   const unsigned int SEED = 42;	// seed for random number generator

eo/tutorial/Lesson2/exercise2.3.cpp

@@ -36,7 +36,7 @@ typedef eoBit<double> Indi;	// A bitstring with fitness double
 
 using namespace std;
 
-void main_function(int argc, char **argv)
+void main_function(int /*argc*/, char **/*argv*/)
 {
 // PARAMETRES
   const unsigned int SEED = 42;	// seed for random number generator

eo/tutorial/Lesson5/eoOneMaxMutation.h

@@ -44,7 +44,7 @@ public:
      * modifies the parent
      * @param _genotype The parent genotype (will be modified)
      */
-    bool operator()(GenotypeT & _genotype)
+    bool operator()(GenotypeT & /*_genotype*/)
 	{
 	    bool isModified(true);
 	    // START code for mutation of the _genotype object

eo/tutorial/Lesson5/eoOneMaxQuadCrossover.h

@@ -46,7 +46,7 @@ public:
      * @param _genotype1 The first parent
      * @param _genotype2 The second parent
      */
-    bool operator()(GenotypeT& _genotype1, GenotypeT & _genotype2)
+    bool operator()(GenotypeT& /*_genotype1*/, GenotypeT & /*_genotype2*/)
 	{
 	    bool oneAtLeastIsModified(true);
 	    // START code for crossover of _genotype1 and _genotype2 objects

eo/tutorial/Lesson5/make_op_OneMax.h

@@ -73,7 +73,7 @@
 */
 
 template <class EOT>
-eoGenOp<EOT> & do_make_op(eoParameterLoader& _parser, eoState& _state, eoInit<EOT>& _init)
+eoGenOp<EOT> & do_make_op(eoParameterLoader& _parser, eoState& _state, eoInit<EOT>& /*_init*/)
 {
   // this is a temporary version, while Maarten codes the full tree-structured
   // general operator input

eo/tutorial/Lesson6/RealPSO.cpp

@@ -12,7 +12,7 @@
 #include <eo>
 
 // Use functions from namespace std
-using namespace std;
+// using namespace std; // Do not do this, this shadows EO's `apply` function.
 
 //-----------------------------------------------------------------------------
 typedef eoMinimizingFitness FitT;
@@ -33,7 +33,7 @@ FitT real_value (const Particle & _particle)
 
 
 
-void main_function(int argc, char **argv)
+void main_function(int /*argc*/, char **/*argv*/)
 {
 // PARAMETRES
  // all parameters are hard-coded!
@@ -114,9 +114,9 @@ void main_function(int argc, char **argv)
   	pop.sort();
 
   	// Print (sorted) the initial population (raw printout)
-    cout << "INITIAL POPULATION:" << endl;
+    std::cout << "INITIAL POPULATION:" << std::endl;
     for (unsigned i = 0; i < pop.size(); ++i)
-	 cout <<  "\t best fit=" <<  pop[i] <<  endl;
+	 std::cout <<  "\t best fit=" <<  pop[i] <<  std::endl;
 
 
 ///////////////
@@ -158,9 +158,9 @@ void main_function(int argc, char **argv)
 // OUTPUT
   // Print (sorted) intial population
 	 pop.sort();
-	 cout << "FINAL POPULATION:" << endl;
+     std::clog << "FINAL POPULATION:" << std::endl;
   	 for (unsigned i = 0; i < pop.size(); ++i)
-	cout <<  "\t best fit=" <<  pop[i] <<  endl;
+     std::clog <<  "\t best fit=" <<  pop[i] << std::endl;
 
 }
 
@@ -173,9 +173,9 @@ int main(int argc, char **argv)
     {
 	main_function(argc, argv);
     }
-    catch(exception& e)
+    catch(std::exception& e)
     {
-	cout << "Exception: " << e.what() << '\n';
+        std::cerr << "Exception: " << e.what() << '\n';
     }
 
     return 1;