Expose objcryst's anisotropic Pseudo-Voigt reflection profile

[clemisch]

pyobjcryst currently uses/exposes only objcryst's isotropic Pseudo-Voigt profile.
objcryst already has an anisotropic PV, which I want not necessarily for being anisotropic, but its finer control of Lorentz vs Gaussian peak shape parameters.

To expose it, we add explicit constructors for the different profiles, and add method PowderPatternDiffraction.SetProfile to assign them (by copy).

from pyobjcryst.reflectionprofile import (
    ReflectionProfilePseudoVoigt,
    ReflectionProfilePseudoVoigtAnisotropic,
)

profile = ReflectionProfilePseudoVoigtAnisotropic()
profile.GetPar("W").SetValue(1e-6)
profile.GetPar("G_HH").SetValue(2e-6)

for pdiff in pp.get_crystalline_components():
    pdiff.SetProfile(profile)

There already exists pdiff.SetReflectionProfilePar which is advertised to be used like

pdiff.SetReflectionProfilePar(ReflectionProfileType.PROFILE_PSEUDO_VOIGT, W)

but it actually ignores the profile type parameter and is hard-coded to create an isotropic PV profile. This PR doesn't change that, to avoid breaking existing code.

[clemisch]

The test is failing because objcryst's constructor for ReflectionProfilePseudoVoigtAnisotropic currently ignores its fwhmGaussP argument.

I proposed a fix in vincefn/objcryst#93.
But the test here won't succeed until a new (lib)objcryst release?
I adapted the tests to get/set the parameters more manually, now they work already.

[vincefn]

But the test here won't succeed until a new (lib)objcryst release?

Yes - have you finished the (lib)objcryst changes ? Then we'll do a release.