nih install -N - do not alter auto-installed flag

plan -1:
- nih leaf -a: ALL leaf packages
- nih uninstall: do not require .nih/pkg_summary.txt (ano)
- nih install -u mark as installed -a autoinstalled
- fix for -L
- fix for wildcard in DEPENDS
- SHA512 with All/ prefix
- multiple pkg_summary(5) (e.g. 5.0-indep)

plan0:
- use distbb for source-based update

plan1:
- configuration variable for ~/.nih
- nih status: -v analyse vulnerable packages against binary or pkgsrc tree
- nih install: ability to check a number bytes to download and
  install/remove
- nih install: ipp -- default repository for OI
- nih status: -N   -- check installed(?) packages
                      against build-time dependencies
- nih install: working with ALL binaries available in $CACHEDIR
- nih clean-distdir

- nih install: use pkg_summary-YYYYMMDD.txt?
- Use pkg_summary-YYYYMMDD.txt
  and use such summaries for in 'nih clean-cache' and 'nih install'
- before update warn about missed binaries for installed packages
  (downgrade will not be possible)

plan2:
- nih remove/install: syslog (idea belongs to Marc Espie)
- nih install: a way to download ALL packages at once
  using different mirrors (for those who have very fast internet connection).
- nih status: -S   -- analyse symbols?
- nih clean-cache:    use FILE_NAME
- autoverifying pkgdb after installation
- separate pkg_install_plan script from nih
- optionally disable REQUIRES/PROVIDES checks
