SplineModel enhancements

[TheBB]

• Ensure a predictable ownership hierarchy is always present, so that e.g. faces between two volumes are owned by the volume that added them first.
• Add functions for generating cell numbers (element numbers) and node numbers (control point numbers) in such a way that objects on interfaces agree on them.
• Add support for naming things (boundaries, topologysets, etc.)
• Avoid using sets internally to get deterministic output.
• Some other quality-of-life functionality.

A short script to demonstrate:

(For extra fun, try reversing or swapping parametric directions on v or q.)

from splipy import *

v = Volume()
q = v + (1,0,0)

model = SplineModel(3, 3)
model.add([v, q])

model[v.section(u=0)].name = 'inflow'
model[q.section(u=-1)].name = 'outflow'
model.assign_boundary('wall')

model.summary()

model.generate_cp_numbers()

print(model.catalogue[v].node.cp_numbers)
print(model.catalogue[q].node.cp_numbers)

print(len(list(model.boundary('inflow'))))
print(len(list(model.boundary('outflow'))))
print(len(list(model.boundary('wall'))))
print(len(list(model.boundary())))

[TheBB]

I just realized the date... this is what you get when living in a country where May 1 is not a public holiday.

[TheBB]

Added function for getting faces, which is the major one for OpenFOAM output.

[TheBB]

Okay, tests are in. This is ready for review.

[TheBB]

To clarify: This adds global numbering of "cells" (defined as gaps in knot vectors, i.e. elements) and control points (what IFEM would call nodes). The face functionality assumes linear geometry, that is to say it equates control points with cell intersection points. I think that's enough for now.

[TheBB]

@VikingScientist I have updated.