Added support for the upcoming `options_first` argument  and implemented a
(perhaps unwarranted) major interface change: all arguments `docopts` accepts
are now options, separated from the arguments to be parsed by a `--`.
`--help=<msg>` is now how the doc string is given to `docopts`.  The optional
version message is given similarly: `--version=<msg>`.  `docopts`'s own
help and version messages can be read by calling it with the respective options
but without any arguments.
The table of contents didn't look so nice on GitHub.
Forgot to replace the old arguments in the documentation here
Changed PATH to $PATH and deleted unnecessary space
Changed -- to : in the usage pattern

Because I think `docopts -h docstring : arguments` looks nicer and, amazingly
enough, docopt actually supports it (now that I can use `options_first`.)
I think docopts is zipsafe?
Update the year in the license file too
Switch to the new language agnostic testing system
Prepare for 0.6.0 release