Allowing automatic keyboard shortcuts setup to match user's familiar ones

[LucileDT]

(see also: #358 (comment))

It would be nice to provide automatically setup keyboard shortcuts to our users by making them match their usual ones.

I propose, on Akira first start, to display a prompt asking the user if they worked with a specific software before, and depending on their choice, setup keyboard shortcuts to be similar to the selected software. This feature is depending on keyboard shortcuts rebinding (so it makes sense to firstly provide keyboard shortcuts customization, and then add this layer of automation).

I will provide mockups as soon as I can to clarify my idea 🙂

This is pretty much linked to Unifying Shortcuts for Akira.