xbps-bin:
 * Add support to install binary packages without any repository.
 * Add a flag to reinstall a package version that is already installed,
   overwritting files on disk and updating required_by if required.
   Perhaps change the automatic-install object to false, like pkg_install
   from NetBSD do.
 * Implement shell style match patterns with fnmatch() for install, update
   and remove.
 * Make -f flag to overwrite files when installing, and to ignore
   files with wrong checksum or unexistent when removing.
   [PARTIAL: only unexistent files are ignored when removing]

libxbps:
 * Add support to upgrade packages but overwritting current files;
   this will fix libc, sh and others. An "essential" boolean obj
   seems to be a good way to find such packages, like dpkg.
   [PARTIAL: files are overwritten but obsolete files are not
    taken into account yet]