Miscellaneous small changes

- Change order of `format`, `subtype` and `endian` function arguments in `format_check`, to be consistent with `SoundFile.__init__` etc.

- Change function argument order of `blocks` so that `blocksize` comes before the `__init__` arguments. This would make the typical usage of this function easier.

- Change function name of `format_check` to `check_format`.