Handle 7- and 9-parameter Hipparcos fits

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This should be straightforward. We just need to modify the Nielsen test to assess the IAD.

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Eric says:

7- and 9-parameter fits are actually trivial to fit with the existing orbitize code: even though the fit on the Hipparcos DVD gives 7 or 9 parameters for these binaries, the residuals are still reported only to the basic 5 parameters (ignoring the t^2 and t^3 terms). So the embarrassingly-named “Nielsen test” will fail unless it’s editted to do the refit with 7 parameters, but the orbit-fitting should work just fine. The only change needed will be to disable the test that stops the code if a solution type other than “5" is detected.

(Solution types “o” (orbit) and “stochastic” (extra noise added to the scan errors) still need special handling, but save that battle for another day)