[cadenmyers13]

Please merge #5 first.

Adding the first two peak profile components, built on the Component helpers:

• PseudoVoigtProfile (the default): U, V, W, eta0, eta1, asym0, asym1, asym2, wrapping pyobjcryst's ReflectionProfilePseudoVoigt.
• TCHProfile: U, V, W, X, Y, Z, P, LGmix, wrapping ReflectionProfilePseudoVoigtTCH. It is symmetric, which is why pseudo-Voigt stays the default for lab data.

Each profile is three short methods. __init__ creates its Parameters from a fresh pyobjcryst profile, with ObjCryst's defaults and limits. install puts a fresh pyobjcryst profile on a pattern's diffraction component, and update pushes the Parameter values into it. pyobjcryst's SetProfile installs a copy, so update always writes into diffraction.GetProfile(). The profiles keep no reference to the pyobjcryst objects, so one profile can serve several patterns. The generator will use that when phases share a profile.

The tests use plain pyobjcryst patterns for PbSO4 (tests/testdata/PbSO4-Wyckoff.cif, from GSAS-II's test inputs), so the profiles are tested before the generator is rebuilt on them. They check that:

• update gives the same pattern as setting the value directly in pyobjcryst.
• Every Parameter lands on its own ObjCryst parameter, which catches a typo or swap in the hand-written name mappings.
• Installing twice is safe.
• One profile updates two patterns.

BackToBackExponentialProfile (time of flight) stays a stub, because pyobjcryst doesn't bind ObjCryst's TOF profile yet.

Also in this PR: a small cleanup of the Component tests from the previous PR. Two one-line fixtures are inlined, and refinable_par_name is renamed to pyobjcryst_par_name for readability. Test behaviour is unchanged.

CI will fail, as on the previous PR: the tests need pyobjcryst main, and the conda-forge release doesn't have these profile classes. Local results, with pyobjcryst built from main:

tests/test_component.py ..............                       [100%]
tests/test_profiles.py ............                          [100%]
26 passed

What should the reviewer(s) do?

Please review the two profiles and their tests.

[cadenmyers13]

@sbillinge ready for review. Please merge #5 first.