Log Message:
Update to 0.15.0

  nih remove:
    - now this command works correctly without external package
      repository

  nih leaf:
    - new option "-u" for printing user-installed leaf packages

  nih status:
    - option -s has been renamed to "-p"

  Primary extension for pkg_summary(5) is now "gz"

  Updates in man.1

  nih.default.conf:
    - update default URLs to package repositories

  root Makefile:
    - +PKG_DBDIR defaults to ${PREFIX}/pkgdb