Support expansion of name attribute in: %feature("interface", name="%s")
%s expands to the proxy class name and all the usual %rename functions
can be used (regex, strip, camelcase etc) to derive the interface name
from the proxy class name.
Rename $interfacename family of special variables to $javainterfacename for Java
Rename $interfacename family of special variables to $csinterfacename for C#
This is to free up $interfacename for simple interface name expansion in forthcoming commit
The C++ type must be last in the argument list to support templates with
multiple arguments which are separated by commas.
Affects DECLARE_INTERFACE and DECLARE_INTERFACE_RENAME.
