ENH: Allow special object constructors to convert arguments.

With this change to the python wrappers, special objects like
vtkVariant can be automatically constructed in order to resolve
method arguments.  So vtkVariantArray.InsertNextValue(vtkVariant v)
can take int, float, string, etc. and the vtkVariant will be
constructed automatically.  Only one level of conversion is allowed.

Common/vtkPythonUtil.h

@@ -67,7 +67,27 @@ typedef struct {
 typedef void *(*PyVTKSpecialCopyFunc)(void *);
 typedef void (*PyVTKSpecialDeleteFunc)(void *);
 typedef void (*PyVTKSpecialPrintFunc)(ostream& os, void *);
-class PyVTKSpecialTypeInfo;
+
+VTK_PYTHON_EXPORT class PyVTKSpecialTypeInfo
+{
+public:
+  PyVTKSpecialTypeInfo() :
+    classname(0), docstring(0), methods(0), constructors(0),
+    copy_func(0), delete_func(0), print_func(0) {};
+
+  PyVTKSpecialTypeInfo(
+    char *cname, char *cdocs[], PyMethodDef *cmethods, PyMethodDef *ccons,
+    PyVTKSpecialCopyFunc copyfunc, PyVTKSpecialDeleteFunc deletefunc,
+    PyVTKSpecialPrintFunc printfunc);
+
+  PyObject *classname;
+  PyObject *docstring;
+  PyMethodDef *methods;
+  PyMethodDef *constructors;
+  PyVTKSpecialCopyFunc copy_func;
+  PyVTKSpecialDeleteFunc delete_func;
+  PyVTKSpecialPrintFunc print_func;
+};
 
 typedef struct {
   PyObject_HEAD
@@ -80,7 +100,7 @@ extern "C"
 {
 VTK_PYTHON_EXPORT int PyVTKObject_Check(PyObject *obj);
 VTK_PYTHON_EXPORT int PyVTKClass_Check(PyObject *obj);
-VTK_PYTHON_EXPORT int PyVTKSpecialObjectCheck(PyObject *obj);
+VTK_PYTHON_EXPORT int PyVTKSpecialObject_Check(PyObject *obj);
 VTK_PYTHON_EXPORT
 PyObject *PyVTKObject_New(PyObject *vtkclass, vtkObjectBase *ptr);
 VTK_PYTHON_EXPORT
@@ -92,12 +112,16 @@ PyObject *PyVTKSpecialObject_New(char *classname, void *ptr, int copy);
 
 // for deciding what method signature to use for overloaded methods
 VTK_PYTHON_EXPORT
-PyObject *PyVTKCallOverloadedMethod(const char *classname,
-                                    PyMethodDef *methods,
+PyObject *PyVTKCallOverloadedMethod(PyMethodDef *methods,
                                     PyObject *self, PyObject *args);
 
+// Find a method that takes the arg
+VTK_PYTHON_EXPORT
+PyMethodDef *PyVTKFindConversionMethod(PyMethodDef *methods, PyObject *arg);
+
 // this is a special version of ParseTuple that handles both bound
 // and unbound method calls for VTK objects
+
 VTK_PYTHON_EXPORT
 vtkObjectBase *PyArg_VTKParseTuple(PyObject *self, PyObject *args, 
                                    char *format, ...);
@@ -131,9 +155,9 @@ PyObject *vtkPythonGetObjectFromObject(PyObject *arg, const char *type);
 // create object given only the class name.
 extern VTK_PYTHON_EXPORT
 void vtkPythonAddSpecialTypeToHash(
-  char *classname, PyMethodDef *methods, char *docstring[],
-  PyVTKSpecialCopyFunc copyfunc, PyVTKSpecialDeleteFunc deletefunc,
-  PyVTKSpecialPrintFunc printfunc);
+  char *classname, char *docstring[], PyMethodDef *methods, 
+  PyMethodDef *constructors, PyVTKSpecialCopyFunc copyfunc,
+  PyVTKSpecialDeleteFunc deletefunc, PyVTKSpecialPrintFunc printfunc);
 
 // Return the pointer to a non-VTK object
 extern VTK_PYTHON_EXPORT