convert: Use clone's behaviour for the default destionation name.
Adjusted the documentation for this and for the fact that the destionation is
created even if a name is specified.
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
See http://www.selenic.com/mercurial/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.