title: Laravel get old input with dot notation
body: <p>My input name is as follows:
  <code>&lt;input name="settings[custom_plan.breakpoint1]"/&gt;</code></p>
  
  <p>How can I retrieve the <code>old</code> input for it? As the dot notation works for the array of the input, but not in the actual name. So <code>old('settings[custom_plan.breakpoint1]')</code> is not working, and neither is <code>old('settings.custom_plan\.breakpoint1')</code> (escaping the dot is working in the validation notation).</p>
  
  <p>How can I retrieve the old value for the input? </p>
  
  <p>Thanks!</p>