Option to have snipe override f/F/t/T
Major refactor

- Removed f/F/t/T overrides (for now)
- Refactor N-character searching (fixes a number of bugs for
  'letters mode)
- Fix backwards no-highlighting bug
- Easier-to-read point adjustment for operator/visual snipes
Rewrote readme for clarity (hopefully)
(v1.2) Major refactor + bugfixes + override f/F/t/T option

+ evil-snipe can override evil-mode f/F/t/T/;/, (more powerful)
  + see option: evil-snipe-override
  + evil-snipe-f/F/t/T have been renamed to evil-snipe-s/S/x/X
  + new evil-snipe-f/F/t/T defuns for replacing native f/F/t/T
+ add option: evil-snipe-repeat-scope to dictate search scope while
  repeating. By default, it's set to 'whole-line.
+ add options: evil-snipe-repeat-nN & evil-snipe-repeat-sS