pkgman search: Add --requirements option

BSolver: Add SetDebugLevel()

In LibsolvSolver set the debug level of the pool.

pkgman: Add full-sync command

* BSolver/LibsolvSolver: Add FullSync() method. It uses libsolv's
SOLVER_DISTUPGRADE mode.
* BPackageManager: Add FullSync() using the new solver mode.
* pkgman: Add full-sync command.

The new command is similar to the update command without arguments, just
more aggressive, allowing downgrading or even removal of packages, to
match the state of the repositories. Just like "update" it doesn't work
properly yet.

BSolver::VerifyInstallation(): Add flags parameter

Only flag ATM is B_VERIFY_ALLOW_UNINSTALL. It tells to solver to suggest
uninstalling packages when necessary instead of considering such a case
a problem.

BSolver: Extend FindPackages() functionality

* Add flag B_FIND_INSTALLED_ONLY to only return installed packages.
* Add FindPackages() version that finds packages like Install() or
Uninstall() do.

BSolver/LibsolvSolver: Add Update()

BSolver/LibsolvSolver: Add Uninstall()

Also fix incorrect check in LibsolvSolver::GetResult().

BSolver/LibsolvSolver: Add problem solution selection support

... and re-solving.

BSolver::Install(): Add optional unmatched specifier return param

BSolver/pkgman: Support for searching in provides

* BSolver/LibsolvSolver:
* Add B_FIND_IN_NAME and make searching in the names explicit.
* Add B_FIND_IN_PROVIDES to search the packages' provides list.
* pkgman: Also search in provides.

BSolver/LibsolvSolver: Add FindPackages()

Given a search string it finds all matching packages.

BSolver: Add VerifyInstallation()

... and implement it in LibsolvSolver.

Flesh out the package kit solver API quite a bit more

* Reorganize things a bit:
- BSolver is now an abstract base class.
- A libsolv based implementation, LibsolvSolver, lives in a new
add-on, which is loaded lazily.
- Get rid of libpackage_solver. Save for LibsolvSolver everything
is moved to libpackage.
- This is a nicer solution for the cyclic dependency caused by
libsolv (libsolvext to be precise) using the package kit for
reading repositories and package files.
* Add a solver result data structure and and an accessor the solver.
* Add problem reporting support to the solver. There aren't data
structures for the problem solutions yet and support for selecting
solutions and re-solving is missing as well.

Beginnings of the PackageKit dependency solver

Not functional (or tested) yet. The libsolv setup for a somewhat
simplified installation case should be more or less complete, though.
The solution conversion to to-be-created Haiku data structures and the
handling of problems is still missing, though.

BSolver: Add SetDebugLevel()

In LibsolvSolver set the debug level of the pool.

pkgman: Add full-sync command

* BSolver/LibsolvSolver: Add FullSync() method. It uses libsolv's
SOLVER_DISTUPGRADE mode.
* BPackageManager: Add FullSync() using the new solver mode.
* pkgman: Add full-sync command.

The new command is similar to the update command without arguments, just
more aggressive, allowing downgrading or even removal of packages, to
match the state of the repositories. Just like "update" it doesn't work
properly yet.

BSolver::VerifyInstallation(): Add flags parameter

Only flag ATM is B_VERIFY_ALLOW_UNINSTALL. It tells to solver to suggest
uninstalling packages when necessary instead of considering such a case
a problem.

BSolver: Extend FindPackages() functionality

* Add flag B_FIND_INSTALLED_ONLY to only return installed packages.
* Add FindPackages() version that finds packages like Install() or
Uninstall() do.

BSolver/LibsolvSolver: Add Update()

BSolver/LibsolvSolver: Add Uninstall()

Also fix incorrect check in LibsolvSolver::GetResult().

BSolver/LibsolvSolver: Add problem solution selection support

... and re-solving.

BSolver::Install(): Add optional unmatched specifier return param

BSolver/pkgman: Support for searching in provides

* BSolver/LibsolvSolver:
* Add B_FIND_IN_NAME and make searching in the names explicit.
* Add B_FIND_IN_PROVIDES to search the packages' provides list.
* pkgman: Also search in provides.

BSolver/LibsolvSolver: Add FindPackages()

Given a search string it finds all matching packages.

BSolver: Add VerifyInstallation()

... and implement it in LibsolvSolver.

Flesh out the package kit solver API quite a bit more

* Reorganize things a bit:
- BSolver is now an abstract base class.
- A libsolv based implementation, LibsolvSolver, lives in a new
add-on, which is loaded lazily.
- Get rid of libpackage_solver. Save for LibsolvSolver everything
is moved to libpackage.
- This is a nicer solution for the cyclic dependency caused by
libsolv (libsolvext to be precise) using the package kit for
reading repositories and package files.
* Add a solver result data structure and and an accessor the solver.
* Add problem reporting support to the solver. There aren't data
structures for the problem solutions yet and support for selecting
solutions and re-solving is missing as well.

Beginnings of the PackageKit dependency solver

Not functional (or tested) yet. The libsolv setup for a somewhat
simplified installation case should be more or less complete, though.
The solution conversion to to-be-created Haiku data structures and the
handling of problems is still missing, though.