Make model modification functions consistent

[exaexa]

For adjusting the models, there should be 3 variants of functions that allow the users to make variants.

Let's assume verb such as "add" and object" such as reaction, the combined function would be called add_reactionoradd_reactions`.

We should have:

1. verb_object and verb_objects with parameters (model, object_description) that returns a modified copy of the model, leaving the stuff in model intact
2. verb_object! and verb_object! with the same parameters that modify the model in-place
3. mod_verb_object with parameters (object_description) that returns a function that behaves like verb_object, for usage in screen().

This should be consistent across all modifications (where sensible). Plural names are preferred where it makes sense, singular ones should be a simple wrappers.

Naming of the 3rd kind of the modifications functions is to be discussed, some possible good choices include:

• mod_add_reaction
• with_added_reaction
• just added_reaction
• with_reaction (requires verb change though)

Cc @stelmo @laurentheirendt

[exaexa]

I'm going with the added_reaction scheme now, may change in the future. It's in 1 file anyway.

[exaexa]

EDIT, nah, with_ is better. :D

[exaexa]

I see this kindof solved itself. :D