title: Send multiline argument to OptionParser
body: <p>I have <code>.rspec</code> file in my project with content something like this:<br>
  <code>--exclude-pattern spec/1_spec.rb, spec/2_spec.rb</code><br>
  There is pretty long line of specs, so I want to split this to several lines, but don't know how.<br>
  <code>--exclude-pattern spec/1_spec.rb, \
  spec/2_spec.rb
  </code>
  seems not working, <code>rspec</code> command give error:
  <code>
  Unmatched double quote: "--exclude-pattern 'spec/1_spec.rb,
  </code>
  What line separator should I use?</p>
  
  <p>UPDATE:
  I found out, that <a href="https://github.com/rspec/rspec-core/blob/master/lib/rspec/core/option_parser.rb#L40" rel="nofollow">rspec uses OptionParser</a> to parse those arguments.
  So I can rephrase my question:<br>
  How to send multiline argument to OptionParser</p>