Display issues for vector variables/parameters in Latexify

[TorkelE]

Simple example:

using Catalyst
@reaction_network begin
    @parameters k[1:2]
    @species (X(t))[1:2]
    (k[1],k[2]), X[1] <--> X[2]
end

produces:

Here:

• For parameters we get getindex(k,i) instead of k_i
• For Species, i is dropped entirely.

Quite a couple of things happens if we change around so that species appear in rates and parameters as reactants:

@reaction_network begin
    @parameters k[1:2] [isconstantspecies=true]
    @species (X(t))[1:2]
    (X[1],X[2]), k[1] <--> k[2]
end

Another vector-variable elated issue, which affects Symbolics and it is useful to keep track of, is JuliaSymbolics/Symbolics.jl#1167

[isaacsas]

This seems fixed with the current release.