Enable C++ use in selection methods.

Enable C++ use in selection methods.

The method that frees the internal data structure for a selection method
now also has the responsibility of freeing the data structure itself.
This makes it possible to allocate the data structure using operator new
in the initialization function, and then correctly free it.

Prerequisite for using C++ types in selection methods before #652 is
implemented.

Change-Id: I99e5a907cbdc4975d20becb0fb1d33e0026c135c