Refactor to remove ndindex.
Backout deprecated sample points dict.
Changes to tests to reflect changes in behaviour
ENH: Test added which demonstrates circular data discrepancy after
rebase.
Confirmed test and updated CML
BUG: Identified discrepancy in interpolated result.
Merge pull request #21 from cpelley/interp_ndindex_refactor

Bill's ndindex stuff

Two tests identify issues with underlying results (one confirmed as being a real discrepancy)