Began porting the mapping system

src/include/serif/mapping/compactification/variation.hpp

@@ -0,0 +1,16 @@
+#pragma once
+
+#include "mfem/linalg/vector.hpp"
+#include "mfem/linalg/densemat.hpp"
+
+namespace serif::mapping::compactification {
+    struct ExteriorMapDirection {
+        const mfem::Vector &displaced_position_variation;
+        const mfem::DenseMatrix &displacement_jacobian_variation;
+    };
+
+    struct ExteriorMapVariation {
+        mfem::Vector physical_position_variation;
+        mfem::DenseMatrix mapping_jacobian_variation;
+    };
+}