Introduce aux efficiency field aux_eff for FC and RES, deprecate Conv alt_eff

[kylecarow]

Resolves #286

Build upon PR #279 (thus related to #287). PR starts at a3b0320

This PR:

• Introduces new Option fields for the FC and RES (where aux load actually comes from) rather than using alt_eff at the powertrain level (which introduces problems for
  • this AuxEfficiency comes with all the standard efficiency range and value checks that PR Reusable code for component efficiencies #279 introduces
  • slightly refined the macro from that PR to add a From impl to easily create constant-efficiency instances
    • could also and a From<Ratio<64>> method as well
• plumbs up FC aux_eff to replace alt_eff for conventional vehicles
• plumbs up RES aux_eff to account for aux load efficiency from batteries (e.g. DC:DC conversion, etc.)
• deprecates alt_eff
  • allows it to still be read, parsed into aux_eff if its not set, and emitting appropriate warnings
  • no longer serialized, defaults to 1.0 (100%) when not provided (i.e. for newly serialized vehicles)

Modeling improvements:

• All conventional vehicles no longer require an alternator efficiency, instead it is handled by the optional FC aux_eff
• HEV/PHEV/BEV can now account for DC:DC conversion, or extra losses for aux load on top of battery efficiency
• HEVs can apply aux load to FC and RES with diffferent efficiencies
• FCEVs when implemented can have None for the aux_eff for fuelconverters, which is more fitting than having a powertrain-level parameter that impacts FC and RES. They still will have no aux load directly supplied by the FC, only the RES, which we can check at runtime Tracking issue for fuel cell electric vehicles #270