- Moved backend determination to `config.el`
- Replaced `pcase` form with only one-arm with `when` or `unless` form
- Refactored function
- Replaccd `(cond ((eq foo) bar))` form with `(pcase (foo bar))`
Improve documentation to be clear about the choices of backends.
Remove obsolete functions.
Make sure that company-lua is only loaded when the right backend is used.
Make keybindings conform to conventions.