- Names ending with len sometimes referred to the buffer size. The same names were used for both buffer size and string length depending on the function in some cases. - Rename str/string to path for generic path functions. - Rename BLI_path_rel arguments (file, relfile) to (path, basename) as it wasn't so clear which is being made relative, `file` can be a directory so rename to `path` (matches naming for BLI_path_abs).