RenRot

When verbosity level set to zero, the program is
now a lot less informative when it dies. All
messages which are not related to the "info" or
"process" category will be put to the standard
error stream.

The option --aggr-virtual-directory was removed,
and you should use --aggr-directory instead. Now
the "#" (hash) symbol can be used at the beginning
of a given color value in a command line. The tree
for an aggregation is created automatically.
Documentation has been updated accordingly.

Serveral bugs were fixed in the aggregation
framework. The hardcoded path separator symbols
are removed. This should bring proper path
interpretation on non-Unix operating systems. The
virtual aggregation now also works for delta
aggregation mode. The documentation has been
updated in accordance with the last changes. A
small optimization was done in the contact sheet
generator.

Thumbnail generation has been added. Aggregation
can be performed with an absolute path now, but on
the same file system. A thumbnail image for the
contact sheet generator can now be in any format
supported by ImageMagick. The plain documentation
was expanded, especially for the contact sheet
generator. The sample directory has been created
with the dotrank and dotkeywords files. A few bugs
were fixed. The --no-ren-rot-tag-mtm option was
renamed to --no-renrot.

A major upgrade was done. The contact sheet generator has been implemented. This new feature requires the Image::Magick Perl module at run-time. In addition to the contact sheet generator framework, the rank functionality has been added. See the applied manual to get details for using it. The configuration parameter "use color" is turned off by default.