Problem
This request was initially made in #163 and is also related to #470. As of #504 bishop88 can accept the thin-film recombination parameters: d2mutau and vbi to output IV curve and its gradients, but there is no propagation of this ability to the proxies that use it such as pvsystem.singlediode()

Solution
Here is a proposed list of methods that should now be able to use these new terms:

• singlediode_methods.bishop88_i_from_v()
• singlediode_methods.bishop88_v_from_i()
• singlediode_methods.bishop88_mpp()
• singlediode_methods._lambertw_v_from_i()
• singlediode_methods._lambertw_i_from_v()
• singlediode_methods._lambertw()
• pvsystem.PVSystem.singlediode()
• pvsystem.PVSystem.i_from_v()
• pvsystem.singlediode()
• pvsystem.max_power_point()
• pvsystem.v_from_i()
• pvsystem.i_from_v()

Alternatives
Please suggest alternative solutions. There has been discussion of refactoring calcparams_pvsyst or even creating model specific singlediode_pvsyst methods. Is that desired?

Additional context
this is a follow on to #504