KaJaSim feature idea: smart auto-complete for rate variables

For user-friendliness, it would be nice if the Javascript proto-IDE would auto-complete (or offer suggestions) for variable names in the context of declaring a rule's rate.

For example, when the user types the something like << ... @ '>> (notice the <<'>>), the system displays a dropdown of variable names (but not of rule names, because <<@ 'rule1'>> would make no sense).
