rm from all factor functions specific ::Tuple{..} on `meas`

[dehann]

This is to allow dispatch use of MixtureRelative. This is good:

function (s::LinearRelative)( res::AbstractArray{<:Real},
                              userdata::FactorMetadata,
                              idx::Int,
                              meas::Tuple,                          # NOTICE HERE
                              X1::AbstractArray{<:Real,2},
                              X2::AbstractArray{<:Real,2}  )

This is bad:

function (s::LinearRelative)( res::AbstractArray{<:Real},
                              userdata::FactorMetadata,
                              idx::Int,
                              meas::Tuple{<:AbstractArray, ...},    # NOTICE HERE
                              X1::AbstractArray{<:Real,2},
                              X2::AbstractArray{<:Real,2}  )

This needs to be done for all factors in the ecosystem as well as noted in the documentation.