Now build SimpleITK into static libs and use (auto)cxx.

cxx/ffi_extra.h

@@ -0,0 +1,20 @@
+#pragma once
+#include <sitkElastixImageFilter.h>
+#include <memory>
+#include <vector>
+
+class ParameterMap {
+public:
+    itk::simple::ElastixImageFilter::ParameterMapType parameters;
+    ParameterMap();
+    ~ParameterMap();
+    explicit ParameterMap(itk::simple::ElastixImageFilter::ParameterMapType parameter_map);
+    void insert(const std::string &key, const std::vector<std::string> &value);
+    [[nodiscard]] std::unique_ptr<std::vector<std::string>> get(const std::string& key) const;
+    [[nodiscard]] std::unique_ptr<std::vector<std::string>> keys() const;
+};
+
+std::unique_ptr<ParameterMap> new_parameter_map();
+std::unique_ptr<ParameterMap> get_default_parameter_map(const std::string& kind);
+std::unique_ptr<ParameterMap> get_transform_parameter_map(itk::simple::ElastixImageFilter& tfilter, unsigned int index);
+void set_parameter_map(itk::simple::ElastixImageFilter& tfilter, const std::unique_ptr<ParameterMap>& parameter_map);