[PATCH] auto rename: best matches and speed improvements

[Herbert Griebel]

# HG changeset patch
# User Herbert Griebel <herbertg at gmx.at>
# Date 1221165456 -7200
# Node ID b99693bd438686e62174098c8d0df05f43e8b1b9
# Parent  6dcbe191a9b51799a4cd40bd398e826bcd9b4dac
auto rename: best matches and speed improvements


This is the first of 4 patches, since they all depend
on each other I will do only the first to minimize the effort.
I did take a look at the mq feature but somehow it was easier
to do the patches in branches and in two different synchronized repos
for easy merging. The pain was when applying patches with
conflicts, and the dependency between the patches.

As requested the other patches will handle:
* name matching
* options to give the user more control of the renaming
* output changes

I dropped the patch for the user feedback since there is
already something else available, something like a generic
progress bar, using backspace characters I guess. So I
will add it later when this is available.

I have added a detailed explanation of the statistics
used for comparing files, it is only slightly complex and has
a detailed explanation so it should be possible to understand it.
It can even be improved using additional values
but I didn't add them yet it keep it simple.
The algorithm has good performance is much faster
than the old even though no name matching is used yet.
The file content comparison has not been changed.