"to_end" positional_arg's shouldn't include other types of arguments (switch, arg, etc.)

[mdwagner]

Getting this weird behavior where positional_arg with to_end: true will include all arguments before or after the positional argument.

Ex (other args before positional):

$ lucky importmap.pin --download -e production -f jspm react react-dom
download? # => true
env # => "production"
from # => "jspm"
packages # => ["--download", "-e", "production", "-f", "jspm", "react", "react-dom"]

Ex (other args after postional):

$ lucky importmap.pin react react-dom --download -e production -f jspm
download? # => true
env # => "production"
from # => "jspm"
packages # => ["react", "react-dom", "--download", "-e", "production", "-f", "jspm"]

If both aren't allowed, then at least the one before the positional_arg should work.
Expected:

$ lucky importmap.pin --download -e production -f jspm react react-dom
download? # => true
env # => "production"
from # => "jspm"
packages # => ["react", "react-dom"]

[mdwagner]

Looking at the code for task.cr and OptionParser (stdlib), it appears you can just use the args passed to parser.parse(args) (which is ARGV be default) and it removes all the arguments parsed, which just leaves the positional arguments. OptionParser also has an unknown_args method for those left over args not parsed, so maybe Lucky can use that instead? Currently, I saw task.cr uses the args from ARGV before they are parsed by OptionParser, which is why they have a reference to them even though OptionParser removes them.