Version 0.3.2.

Features:
* Add `format_volume` function for initializing a FAT filesystem on a partition
* Add more checks of filesystem correctness when mounting

Fixes:
* Clear directory returned from `create_dir` method - upgrade ASAP if this method is used
* Fix handling of FSInfo sector on FAT32 volumes with sector size different than 512 - upgrade ASAP if such sector size is used
* Use `write_all` in `serialize` method for FSInfo sector - previously it could have been improperly updated