Don’t set default options as explicit keys

[denisdefreyne]

By setting default values for options explicitly, i.e. using #[]=, it becomes impossible to distinguish beteen explicity-specified options and implicitly-defaulted options. By using Hash#new, it becomes possible to return default values but not have them explicitly set as keys.

For example:

option :a, :animal, 'add animal', default: 'giraffe', argument: :required

run do |opts, args, cmd|
  puts "Animal = #{opts[:animal]}"
  puts "Option given? #{opts.key?(:animal)}"
end

% ./run --animal=donkey
Animal = donkey
Option given? true

% ./run --animal=giraffe
Animal = giraffe
Option given? true

% ./run
Animal = giraffe
Option given? false

See #94.

[denisdefreyne]

Marking as WIP because this change causes some pdk tests to fail.

[denisdefreyne]

Here’s a fix for pdk: puppet/pdk#674

[pcarlisle]

I've tested this with r10k and it solves my problem