Decouple Yi.Keymap.Cua from Yi.Keymap.Emacs

[waivio]

I believe that my distro is having issues packaging Yi.Keymap.Cua because of it's dependency on the Emacs keymap. I was thinking of helping resolve this by making a Yi.Keymap.Cua.KillRing and Yi.Keymap.Cua.Utils duplicating the code from the Yi.Keymap.Emacs.KillRing and Yi.Keymap.Cua.Utils. I've made these simple changes and updated the cabal file and it seems to compile. Should I generate a pull request? Or should the KillRing and Utils code be refactored somewhere else?

[codygman]

@waivio I'm not very involved in the Yi project, but in general it's better to submit a PR and your question at the same time so everyone can see the code too. Worst case scenario is that your PR is closed, but even closed PR's could be useful to someone else.