[PATCH] auto rename: best matches and speed improvement UPDATE6

[Herbert Griebel]

I have again updated the matching algorithm. I would have never
thought that I will spend so much time on this, so sorry for the
many updates.

Statistics of the file content could again speed up the matching
considerably. I also found a distance metric for the difference
between two files, which can eliminate unnecessary comparisons
(it's not a cyclic measure like a CRC).

I am now trying to make a better pathname matching for renaming
identical files in different folders, so please ignore the last
update.