Add source files

explelibx-mgrid/exple-mul.cpp

+#include "exple-mul.h"
+
+int exple::mul(int a, int b)
+{
+  int result = 0;
+
+  for (int n = 0; n<b; n++)
+  {
+    result += a;
+  }
+  return result;
+}

explelibx-mgrid/exple-mul.h

+namespace exple
+{
+  int mul( int a, int b);
+}