c-library functions should be always present, documented, and lowercase

src/library.h

@@ -256,9 +256,7 @@ void lammps_force_timeout(void *handle);
 int lammps_has_error(void *handle);
 int lammps_get_last_error_message(void *handle, char *buffer, int buf_size);
 
-#ifdef LMP_PYTHON
-int lammps_PYTHON_API_VERSION();
-#endif
+int lammps_python_api_version();
 
 #ifdef __cplusplus
 }