Fix normal writing with evil-write
Remap `competion-at-point` to `evil-ex-completion` in ex (fix #440).

After a first TAB a call to `completion-at-point` activates
`completion-in-region-mode`, which overwrites Evil's TAB bindings. The
additional remapping ensures that `evil-ex-completion` is always used
instead.
do not remove `evil-refresh-undo-step` from `post-command-hook`

It is never added to this hook.
add new possible value `fine` to `evil-want-fine-undo` (fix #444)

This value causes Evil to behave as if `evil-want-fine-undo` is t but
merges the deletion of a change operator with the first subsequent
insertion. This is implemented by removing only the first undo
boundary in `evil-refresh-undo-step`.
remove bindings from `minibuffer-local-map`