An alternative "Save field settings and stay" submit button

The attachment isn't a patch rather an independent module which adds the requested functionality through form_alter the most unobtrusive fashion.
This is a must have feature, since some settings require to do a first save, then return to the field settings page to set another settings (e.g. when using taxonomy have to select first the vocabulary then return to setup the default value, also when default value is provided with PHP code and didn't work as expected).
Enabling the attached module just will add an alternative button which doesn't redirect out of the field settings page, everything else remain the same.