Cleaned up examples in reduction tutorials

Documentation/Tutorials/ReductionAndScan/ExclusiveScanExample.cpp

 #include <iostream>
 #include <cstdlib>
 #include <TNL/Containers/Vector.h>
-#include <TNL/Containers/Array.h>
-#include <TNL/Containers/Algorithms/Reduction.h>
-
-#include <TNL/Containers/StaticVector.h>
 
 using namespace TNL;
 using namespace TNL::Containers;

Documentation/Tutorials/ReductionAndScan/MapReduceExample-1.cpp

@@ -2,7 +2,6 @@
 #include <cstdlib>
 #include <TNL/Containers/Vector.h>
 #include <TNL/Containers/Algorithms/Reduction.h>
-#include <TNL/Timer.h>
 
 using namespace TNL;
 using namespace TNL::Containers;
@@ -20,7 +19,6 @@ double mapReduce( Vector< double, Device >& u )
 
 int main( int argc, char* argv[] )
 {
-   Timer timer;
    Vector< double, Devices::Host > host_u( 10 );
    host_u.evaluate( [] __cuda_callable__ ( int i ) { return sin( ( double ) i ); } );
    double result = mapReduce( host_u );

Documentation/Tutorials/ReductionAndScan/ScanExample.cpp

 #include <iostream>
 #include <cstdlib>
 #include <TNL/Containers/Vector.h>
-#include <TNL/Containers/Array.h>
-#include <TNL/Containers/Algorithms/Reduction.h>
-
-#include <TNL/Containers/StaticVector.h>
 
 using namespace TNL;
 using namespace TNL::Containers;

Documentation/Tutorials/ReductionAndScan/SegmentedScanExample.cpp

 #include <iostream>
 #include <cstdlib>
 #include <TNL/Containers/Vector.h>
-#include <TNL/Containers/Array.h>
-#include <TNL/Containers/Algorithms/Reduction.h>
-
-#include <TNL/Containers/StaticVector.h>
 
 using namespace TNL;
 using namespace TNL::Containers;

Documentation/Tutorials/ReductionAndScan/SequentialSumWithLambdas.cpp

 double sequentialSum( const double* a, const int size )
 {
    auto fetch = [=] (int i)->double { return a[ i ]; };
-   auto reduce = [] (double& x, const double& y) { x += y; };
+   auto reduce = [] (double& x, const double& y) { return x + y; };
 
    double sum( 0.0 );
    for( int i = 0; i < size; i++ )
-       reduce( sum, fetch( i ) );
+       sum = reduce( sum, fetch( i ) );
    return sum;
 }
 

Documentation/Tutorials/ReductionAndScan/SumExample.cpp

 #include <iostream>
 #include <cstdlib>
 #include <TNL/Containers/Vector.h>
-#include <TNL/Containers/Array.h>
 #include <TNL/Containers/Algorithms/Reduction.h>
 
-#include <TNL/Containers/StaticVector.h>
-
 using namespace TNL;
 using namespace TNL::Containers;
 using namespace TNL::Containers::Algorithms;