Select files for incremental indexing

Hi, peoples!

You are doing great work. But I have found that Your program doesn't have
the right way to select files for incremental indexing.

Using -N switch for indexing files newer than supplied one is a wrong
way for POSIX filesystem in much cases:
1-st is renamed directory: when You rename some part of path to file
(like dir1/dir2/dir3/file -> dir1/dir2newname/dir3/file) no timestamps
associated with file is updated.

Method with symlinks is also wrong: let's assume we have two directories
with files of same name at it (dir1/dir2/file and dir1/dir3/file) then
renamed dir1/dir2 -> dir1/dir4 and dir1/dir3 -> dir1/dir2. Your symlinks
doesn't help with it.

2-nd is that mtime can be changed by utimes() syscall and if You unpack
tarball into your tree it will use it. With POSIX systems we need use
ctime instead of mtime. With windows backup software uses 'archieve'
attribute (windows have 'file creation time' instead of ctime).

There is a method to solve thiese issues with POSIX filesystems, and I
don't know method for windows. This method is used in GNU tar (see
option --listed-incremental from info tar).

I can add more details and some nightmare-quality script in perl if it
seems interesting to You (really I think it must be rewritten in C).

WBR
Dmitri Ivanov