Table Extrapolation

[michael-petersen]

In both exptool.basis.eof and exptool.basis.spheresl, extrapolating to radii outside of the tabulated values gives false potential values. Check against original algorithm.

[michael-petersen]

These do match the original algorithms -- the last bin in the table will be used. This may be an inherently dangerous choice, so we could add warnings.

Closing this for now.