Closes #178.

Closes #156.

The recommendation doesn't work with bash 4.1.5, the code in autojump.bash is fine, so use it here.

I've updated the documentation to notify end users to add compinit to their
~/.zshrc if they want tab completion.

--stat added, jumpstat alias removed.

Options passed to the `j` function will now be passed on autojump. As a result,
directories beginning with `-` are no longer supported.

A -s short alias for --stat is added. Instead of using jumpstat, use `j --stat`
or `j -s` instead.

Not sure if this is correct, is there a source file I should update
instead?

Documentation and install scripts now instruct older Python users to upgrade
their Python version or install older versions of autojump.

'install.sh' now gets a -f|--force option, which makes the install ignore
Python dependency requirements.

2.6.

This was caused by the rewrite to use argparse over optparse to handle command
line arguments.

directory weights within the database.

Documentation is now generated through Pandoc by running ./make_doc.sh.

Man page is generated from manpage.md, while INSTALL.md + manpage.md =
README.md.