Remove unused headers.

Framework/Kernel/src/Statistics.cpp

@@ -11,11 +11,8 @@
 #include <stdexcept>
 #include <functional>
 
-#include <functional>
-
 #include <boost/accumulators/accumulators.hpp>
 #include <boost/accumulators/statistics/mean.hpp>
-#include <boost/accumulators/statistics/median.hpp>
 #include <boost/accumulators/statistics/min.hpp>
 #include <boost/accumulators/statistics/max.hpp>
 #include <boost/accumulators/statistics/variance.hpp>