Add support for parsing C++11 =delete and =default

Although this was documented as working, it wasn't implemented
%typemap(default) failed without the idstring changes
Add some C tests using the C++ keyword delete

Examples/test-suite/c_delete_function.i

@@ -0,0 +1,7 @@
+%module c_delete_function
+
+/* check C++ delete keyword is okay in C wrappers */
+
+%inline %{
+double delete(double d) { return d; }
+%}