Translations:Compile on MinGW/72/en

Modify the following files: Add DLL_HEADER to class MeshOptimize2d Add DLL_HEADER to CalcSurfacesOfNode Add DLL_HEADER to classes SurfaceElementIndex, MeshPoint, Element2d (int anp), Add DLL_HEADER to classes Line, OCCGeometry, OCCParameters, OCCGenerateMesh Add DLL_HEADER to classes OCCSurface, Meshing2OCCSurfaces, MeshOptimize2dOCCSurfaces, OCCRefinementSurfaces Run the configure script with these arguments
 * libsrc/meshing/improve2.hpp
 * libsrc/meshing/meshclass.hpp
 * libsrc/meshing/meshtype.hpp
 * libsrc/occ/occgeom.hpp
 * libsrc/occ/occmeshsurf.hpp