[WIP][RC] Display keybinding names translated

One part of fixing #8509
I hope i have injected in right place.

I have noticed than ```static const std::string default_context_id("default");``` is differs from data/raw/keybindings.json default context "DEFAULTMODE". Is there two default context?

About length of actions names:
It's possible to move all color hints in to "Help of keybindings". There is enough place to fit these messages. And add right aligned "To help press ?" message on first string.
Something like that:
![keyb](https://cloud.githubusercontent.com/assets/5244047/3889015/92c50b56-2207-11e4-8abc-6f7e618b5ef8.png)
It's help of keybindings menu on screen.
Right now i don't know it's possible to do or not.