Shiboken should support creating bindings for explicit instantiations of template classes

Shiboken is presently not capable of supporting creating bindings for classes that derive from classes that are templated - with an explicit instantiation of the class.  This is something that Boost.Python and pybind11 support.

Also, it should be documented somewhere that currently Shiboken is not capable of processing templated classes.

(This bug changed from "Shiboken should support template classes" to the current, more manageable request to support classes with explicit instantiations of templated classes)