Adding reaction network name as option?

[TorkelE]

Currently, network names are added as

@reaction_network rn_name begin
    ...
end

Given that we now support options, it would be possible to do

@reaction_network begin
    @name rn_name
    ...
end

It doesn't really matter, both approaches work. Generally, the first one is neater. However, it is a bit funny that reaction network names is the one input type which is inputted differently compared to all other ones. Moving to the second one would allow us to have a single uniform approach.

I have no strong opinions, but at least something one can consider.