Waveform

Ripple waveform models, exposed under jim's historical Ripple* names.

ripplegw's only construction path is the name-based registry ripplegw.waveform(name, **config) -- concrete classes (IMRPhenomD, TaylorF2, ...) are intentionally not exposed at its top level. These are thin functools.partial bindings onto that registry, so the rest of jim can keep constructing models as RippleIMRPhenomD(f_ref=20.0).