[vim] A couple of workflow-related changes

- Setting all non-focused windows to shrink down to five lines and the
  focused window to take up everything that's left (At least 84 columns
  and the others shrink to accomodate).
- Only highlight the current line and 80th column of the currently active
  window.
[vim] Modified keybinds for pane navigation

- Easier pane navigation with ctrl-hjkl