Uniform point clouds

[kaipartmann]

Currently, a point cloud is assumed to be arbitrary distributed in space. However, if it could be guaranteed that it is uniformly distributed with a known point spacing, this would allow for performance improvements and other things like volume correction, see #32 (comment).

[kaipartmann]

Draft:

abstract type AbstractDiscretization end

struct PointCloud <: AbstractDiscretization
    position::Matrix{Float64}
    volume::Vector{Float64}
end

struct UniformPointCloud <: AbstractDiscretization
    ΔX::Float64
    position::Matrix{Float64}
    volume::Vector{Float64}
end