TODO

proper support for short name decoding from the OEM codepage
marking volume dirty on first write and not-dirty on unmount
support for a volume label file in the root directory
format volume API
add method for getting DirEntry from a path (possible names: metadata, lookup)
add time provier so the crate writes a proper timestamps when chrono is unavailable
do not create LFN entries if the name fits in a SFN entry