Add linkDirectionalParticleObject property

[neilrackett]

At present, it is not possible to customise the Three.js object used for the directional particles

I would like to be able to assign a custom Three.js object to the directional particles using a linkDirectionalParticleObject property in the same way I can for nodes using nodeThreeObject.

[vasturiano]

@neilrackett thanks for reaching out, and sorry for the hold in answering here.

I've just added support for this attribute to provide custom objects for the particles. It's called linkDirectionalParticleThreeObject and it's available in the latest (1.78) version.