Forgot to reset per-name penalty when it got locked by apply_decision.
This also fine tunes compare_package_preference() to always prefer
packages specified on command line speeding up calculation certain
complicated solutions.
Previously we would cache the penalty when evaluating the final
solution, and adding that until we backtrack to first topology
position changing that penalty. However, we can just keep track
of minimum penalty based on name state, and add it. This allows
us to bail out early on bad branches because we know in advance
how things will turn out.
Allow to select packages that conflict in case we are looking for
errors. This allows 'add --force' to install (on boot) the set of
packages with minimum conflicts.
* the solver no longer does look-ahead locking of names
(could be possibly optimized later); instead names are now
always ordered strictly to properly detect the package names
which are unsolveable
* basic error tests added, so we can see the most likely problem
in dependencies easily
Timo Teräs