Multiple keys/buttons per command/action

Most games these days support multiple access methods on a per-command basis; I'm having trouble remembering the last time I saw one that didn't.

E.g., I'd like to retain my right-click as "Inventory" but also assign "I" to this. Ideally "M" for "map", too.

Another common behavior is to leave the default WASD movement keys, but also add the four arrow keys (many games come pre-configured that way, and it might makes sense for OpenMW, too).

I don't know if it's feasible in pre-1.0 to have these options in the interface (which is modelled pretty closely on Bethesda's), or only as config file options.

(RM-4335 from redmine: created on 2018-03-03 by Dark Locq, )