adds higher possible values for interpolation

cpp/particles/particles_system_builder.hpp

@@ -39,8 +39,8 @@
 #include "field.hpp"
 #include "kspace.hpp"
 
-const int MAX_INTERPOLATION_NEIGHBOURS=5;
-const int MAX_INTERPOLATION_SMOOTHNESS=3;
+const int MAX_INTERPOLATION_NEIGHBOURS=6;
+const int MAX_INTERPOLATION_SMOOTHNESS=4;
 
 //////////////////////////////////////////////////////////////////////////////
 ///