Don't apply %ignore to parameters

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.

Examples/test-suite/ignore_parameter.i

@@ -8,12 +8,15 @@
 
 %typemap(freearg) char* a ""; // ensure freearg is not generated (needed for Java at least)
 
+%ignore unignorable;
+
 %inline %{
 // global function tests
 char* jaguar(char* a, int b, double c) { return a; }
 int lotus(char* aa, int bb, double cc) { return bb; }
 double tvr(char* aaa, int bbb, double ccc) { return ccc; }
 int ferrari(int bb) { return bb; }
+int fiat(int unignorable) { return unignorable; }
 
 // member function tests
 struct SportsCars {
@@ -21,6 +24,7 @@ struct SportsCars {
   int astonmartin(char* aa, int bb, double cc) { return bb; }
   double bugatti(char* aaa, int bbb, double ccc) { return ccc; }
   int lamborghini(int bb) { return bb; }
+  int maseratti(int unignorable) { return unignorable; }
 };
 
 // constructor tests

Examples/test-suite/python/ignore_parameter_runme.py

@@ -8,12 +8,14 @@ check(jaguar(200, 0), "hello")
 check(lotus("foo", 1), 101)
 check(tvr("bar", 2), 8.8)
 check(ferrari(), 101)
+check(fiat(17), 17)
 
 car = SportsCars()
 check(car.daimler(200, 0), "hello")
 check(car.astonmartin("foo", 1), 101)
 check(car.bugatti("bar", 2), 8.8)
 check(car.lamborghini(), 101)
+check(car.maseratti(289), 289)
 
 MiniCooper(200, 0)
 MorrisMinor("baz", 0)