It seems `collect` defaults to collecting into an array which doesn't work with a collection of `String`s because `String`s vary in size and their size cannot be known at compile time. To work around this I collect the args into a `Vec` instead and pass that in. Also I think the first call to `matches` was missing an `&` on the `args` parameter.
There was a lot of stuff added here. The most important addition is
how Pirate now returns a MissingArgument kinded error if a required
program argument isn't passed to the program.
