Support keypress events with non-ascii chars

[tomaka]

Original: rust-windowing/glutin#625

[francesca64]

I'm not really sure what's wanted here. The use case of the person who made the issue originally seems to be best solved using scancodes.

[est31]

Scancodes are hardware dependent. You got no way of printing a name for the key or anything. If you shouldn't use keycodes, why do they exist in the first place?

[tomaka]

The "name of the key" is supposed to be the virtual key code which is reported alongside with the scancode in every event.

[Ralith]

It would be useful to support querying a human-readable key name from the OS for a given scancode. This would reduce the demand for ridiculously many virtual key codes, and be more convenient/correct for UI purposes besides.

[Osspial]

Closing in favor of #753 and #812