AFNI Interfaces Refactor

Use cases

1. out_file not set

   -prefix is set to default_out.ext where ext is file extension taken from outputtype AFNICommandLineInputSpec field and default_out depends on the interface.

2. out_file is set to something.nii or something.nii.gz

   -prefix is set to something.nii or something.nii.gz regardless of outputtype AFNICommandLineInputSpec field

3. out_file is set to something (without extension)

   -prefix is set to something.ext where ext is file extension taken from outputtype AFNICommandLineInputSpec field