Fix keymap declarations

The keymaps as declared in previous versions were not creating certain bindings, most egregiously the binding of the enter/return key to `idris-repl-return` in `idris-repl-mode`. Changed most of these to use `[?\...]` form instead of `[name]` form, which is consistent with most of the other keybinding definitions and works for me.
As a bonus, this also corrects the location of a misplaced parenthesis.