Polishing off 3D Classic support in data.py
Adding parameter checking, defaults for 3D; cleanup too
Reverting changes to data.py.  Does this matter?
Merge pull request #46 from gradylemoine/master

3D parameter checking and defaults
Merge remote-tracking branch 'upstream/master' into rjl

* upstream/master:
  Reverting changes to data.py.  Does this matter?
  Adding parameter checking, defaults for 3D; cleanup too
  Polishing off 3D Classic support in data.py