Incidence relation

[blegat]

It would be nice to implement list of point indices inside the hyperplane of an halfspace index. There could be a default implementation similar to

Polyhedra.jl/src/redundancy.jl

Lines 71 to 74 in 8151b9e

	for h in hreps(p)
	if v in hyperplane(h)
	count += 1
	end

but library could implement a more efficient implementation if they already have this information.