2.0
 - Re-implemented in C++(0x).
 - A tutorial is now available.
 - Added a support for multiple upstream tarballs in source packages.
 - More descriptive error messages for errors in configuration files.
 - Implemented refusing expired Release files.
 - New wget-based download method for http(s)/ftp.
 - Implemented dpkg action priority heuristics to reduce the time from the
   package state is changed till the package state is final.
 - New configurable score calculation system in the native resolver
   (new option group 'cupt::resolver::score::*').
 - When no solutions were found, throw an error with a solution tree(s) to
   show why.
 - Automatically determine packages which need an indirect upgrade, making the
   option 'cupt::worker::allow-indirect-upgrade' unneeded.
 - Added an ability to specify additional package expressions and restart the
   solving process in the action preview prompt (new choice 'a').
 - Don't use randomization anymore for implementing
   'cupt::worker::archives-space-limit' option. Deleted option
   'cupt::worker::archives-space-limit::tries'.
