Undo replacement done in replace state at once (fix #330).

Replace state records all modifications as one single undo step like
insert state (unless `evil-want-fine-undo` is set to t).
Start `reftex-select-label-mode` in emacs state (fix #331).
Ignore `undefined` for repetition (re #332).

This special function is called if some key binding is undefined, so
the corresponding key sequence should not be recorded.
Handle simultaneous insertion/deletion insertion tracking (fix #333).

Certain operation may generate buffer changes that do a simultaneous
deletion and insertion, i.e. they generate an after-change-functions
event with beg < end and len > 0. The function
`evil-track-last-insertion` did not handle these cases well but simply
reset insertion tracking. The command `evil-paste-from-register` is a
command that generates such buffer changes, thus failing to work
together with insertion tracking.