Remove helm-quick-update

It is not needed anymore since helm-candidate-number-limit is
small (less than several thousands). If this is the case, then there's
no difference between quick update and no quick update execution time.
Enabling helm-quick-update makes helm buffer flashing for every entered
character to retrieve new candidate list, which would annoy user.
New documentation on escaping in readme
Fix typos in contribute
Add evil-args and evil-jumper to the list of plugins in readme
Add doc for <layer>-excluded-packages variable in readme
Merge branch 'develop' (v0.9.1)