Should the background be exported in FitResult?

[HKaras]

Currently, it is quite complicated to calculate the background fit for plotting. Especially when using multiple-pathways often requiring commands such as:

Bfcn = lambda lam1,lam5,reftime1,reftime5,conc: results.P_scale*(1-lam1-lam5)*dl.bg_hom3d(t-reftime1,conc,lam1)*dl.bg_hom3d(t-reftime5,conc,lam5)
Bfit = results.evaluate(Bfcn)
Bci = results.propagate(Bfcn).ci(95)

Proposal

That the following outputs be added to FitResult:

• FitResult.bg
• FitResult.bgUncert

This is quite a dipolar specific application, and it should be possible to implement in such a way that for non-dipolar models and cases where there is no background that this isn't released.

[HKaras]

This would also close the issue of #472 as it would be no longer relevant

[stestoll]

This seems practical and reasonable.