use new orientation definition for asymmetric shapes

[Paul Kienzle <pkienzle@…>]

In b00a646c6ab83c01056acef9b46d1e392433af0b/sasmodels:

orientation: use new orientation definition for asymmetric shapes. Refs #890.

[Paul Kienzle <pkienzle@…>]

In 61104c829b100869b42c1afd75f30ed30a934cd1/sasmodels:

elliptical cylinder: adjust to new asymmetric orientation definition. Refs #890.

[Paul Kienzle <pkienzle@…>]

In 50beefeac18f2f952bf0863526ec9bbd3009e29c/sasmodels:

paracrystal: adjust to new asymmetric orientation definition. Refs #890.

[Paul Kienzle <pkienzle@…>]

In d6050806338b4bcae5a997acb08f4b1e7e14dd36/sasmodels:

parallelepiped: adjust to new asymmetric orientation definition. Refs #890.

[Paul Kienzle <pkienzle@…>]

In 92dfe0c540274c8b800a9929c3f1e1a7d4cba9dc/sasmodels:

core shell parallelepiped: adjust to new asymmetric orientation definition; start fixing docs. Refs #890.

[Paul Kienzle <pkienzle@…>]

In 68dd6a95741269738dcbfb051d93fe9f26b89c43/sasmodels:

triaxial ellipsoid: adjust to new asymmetric orientation definition; reimplement 1D model from Finnigan and Jacobs, 1971. Refs #890.

[richardh]

triaxial ellipsoid and the parrallelepiped models still need modifications to their effective radius calculation.

triaxial_ellipsoid no longer asks users to keep A<B<C, For ER() need sort so that a≤b≤c; then if b is closer to a than to c, then we are prolate, a,b are equatorial axes and c is polar; else for oblate, a is polar and b,c are equatorial. Note this then uses ER() for ellipsoid, which has different calcs for oblate & prolate.

The paralleliped ER() uses that for cylinder, which seems not to have different version for rod and disk. But likewise we could sort the axes for ER() which would possibly remove the a<b<c requirement on theses models, but this needs testing!

Summary of what Paul K has already done in this ticket, apart from sorting the 2d I(Q) calculation:

major refactoring of calc of I(Q) in - core_shell_bicelle, ellipsoid

redone equations in docu in - ellipsoid, triaxial_ellipsoid

[richardh]

In 4b0a294be46e951df4767202737d3e713c14ee28/sasmodels:

docu improvements re #890

[richardh]

There are some notes in elliptical_cylinder about how many bins to use for orientational averages, these should be reviewed when we have he new integration scheme.