------------------
+ 9: Added the :command:`update` command.
+ 11: Added VCS support.
+ 12: Command-line options in requirement file are allowed.
+ 16: Added the :option:`--no-scripts` and :option:`--no-data` options to the `install` command.
+ 17: Added the possibility to install packages from directories.
+ 23: Comments in requirement file are allowed.
+ Added :class:`pyg.inst.Updater`.
+ Added a new file for the command-line options parser.