add check to ensure inverse projection is defined, before calling it (needed to prevent segfaults for proj versions 4.9.2 and before).
add check to ensure inverse projection is defined, before calling it (needed to prevent segfaults for proj versions 4.9.2 and before).

pyproj4/pyproj,pyproj4/pyproj,ocefpaf/pyproj,ocefpaf/pyproj