Complete core profile extrapolation tool so it can provide a quantity like density vs. (R,Z)

[eldond]

• [x] Quantity vs. rho from the SOLPS run, covering the pedestal
  • [x] Need to extract the relevant slice, such as the outboard midplane. This is covered under https://github.com/ProjectTorreyPines/GGDUtils.jl/issues/3
  • [x] Need to know rho(R,Z) for the SOLPS cell locations
• [x] Extrapolate from pedestal to magnetic axis
• [x] Map a quantity(rho) to quantity(R,Z)
  • [x] Need EFIT map relating rho to R,Z
  • [x] Need a simple function for doing the mapping of the quantity

[eldond]

This should be working now.