cleanup alternate keyboard layout support (Dvorak, Colemak, etc)

[jas4711]

The Dvorak support today is done in a hackish way, and it is not well defined in the protocol how it works. We should clarify the protocol wrt alternative keyboard layouts and implement it, with support for some other keyboard layouts (e.g., Colemak).

[jas4711]

We are interested in discussing and reviewing patches from external sources on this. Please help work on this if you are interested.

[tgulacsi]

Colemak: "cbdp;ghkniojrfuv"

But according to https://en.wikipedia.org/wiki/Keyboard_layout#Colemak , a lot of different layouts are there... Can't we (the hardware) advertise itself as a QWERTY layout?

[thomwiggers]

An alternative yubikey PAM implementation has solved this problem like this: https://github.com/firnsy/yubipam/commit/ebc562c374028773592f4f2e96a8181195df822e