[fastfat_new]

[fastfat_new]
- Fail with an error if file can't be opened.
- Implement FatCreateDcb, actually create DCBs for all parsed directories in the path.
- Set file size in an advanced FSRTL header for a file.
- Implement a small helper function for setting full names in FCB/DCB like it's done in the reference driver.

svn path=/trunk/; revision=43256