pngtile.application: introduce IMAGE_TYPES, and split off image file validation into get_image(), and rename lookup_path() to handle dirs as well
#ifndef PNGTILE_ERROR_H
#define PNGTILE_ERROR_H
/**
* @file
*
* Obtuse error handling
*/
#include "pngtile.h"
#include <errno.h>
#define RETURN_ERROR(code) return -(code)
#define RETURN_ERROR_ERRNO(code, errn) do { errno = (errn); return -(code); } while (0)
#define JUMP_ERROR(err) do { goto error; } while (0)
#define JUMP_SET_ERROR(err, code) do { err = -(code); goto error; } while (0)
#define JUMP_SET_ERROR_ERRNO(err, code, errn) do { err = -(code); errno = (errn); goto error; } while (0)
#endif