redding/ns-options — pull request #56 by kellyredding (2012-11-08 23:18:24+00:00)
Title: Immutable :value options

Specifying an option with the `:value` rule makes it immutable.

```ruby
option :whatever, :value => 'idontcare'

thing.whatever #=> 'idontcare'
thing.whatever = 'huh' #=> NoMethodError ...
thing.whatever 'huh' #=> ArgumentError ...
```