Fix regression introduced by 3f5c17824c
which resulted in using "$ignore" instead of the real parameter name in
Python if an %ignore/%rename($ignore) for the parameter name was used
(as could happen not necessarily intentionally when using wild card
ignores with regex matches) by explicitly checking if we're dealing with
a parameter node in apply_rename(), used by Swig_name_make(), and not
renaming it to "$ignore" in this case.
Extend the test suite to check for this case.
Closes#1460.
