RF+DOC: update afni_utils to build prep-afni-surf standalone + update documentation
BF: fix bug determining slices in lightbox.py (#221). Thanks fto grlee77 to point this out and describe a fix
ENH: allow ProductFlattenMapper to provide explicit names of factors in the constructor
Merge pull request #222 from nno/_enh/afni_utils

RF+DOC: update afni_utils to build prep-afni-surf standalone
Merge pull request #224 from nno/_enh/flatten

 enh/flatten