DOCS, Meaning of: Factors, Likelihoods, Potentials, Partials

[dehann]

Define what is meant with these Nouns:

• Factors: as captured in factor graph,
• MessageLikelihood, a joint belief message propagating on the tree,
• Potential, all likelihoods needed for a subgraph solve (Markov Potential)
• Partial, a factor or likelihood that only constrains some of the dimensions

Related

• #675 (where to store msg channels)
• #679 (consolidate subgraph functions)

Code

• https://github.com/JuliaRobotics/IncrementalInference.jl/blob/7c03d00d40281f64db074340adcd44df26031b3c/src/JunctionTreeTypes.jl#L237-L242

[dehann]

also needs to be added to the verbNoun definitions wiki.