zerofill Files

zerofill 0.5.1
==============

Changed default behavior to wipe inodes before overwriting other unused space,
which benefits if the file system has a journal. Also tried a few other things,
such as renaming all temporary files to the very same name and using utimes()
to set atime and mtime to 0 before deletion, but that didn't gain anything.

zerofill now also closes each temporary file created during inode wipe right
after creation, consuming less memory while wiping inodes.