Checked and updated wavefront tutorials

There were a few bugs due to a change in the wvf functions from 'wave' -> 'calc wave'

The chromatic aberration tutorial was a stub saying that one should be written, so deleted that.

Moved these from xNeedsFiling into the top level wavefront directory.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>