nx-mongo: - fixed suprising compiler message "alignment of array elements is greater than element size" when using e.g. "bson_iter_t i[1]" - some c-code cleanup - tested with mongodb-c-driver 0.92.3
- since mongoc_gridfs_get_files is supported since today by the mongo-c-driver, we do not need it private implementation any more. all dependencies on private header files are removed by now.