Close #11

* Turn off auto-complete by default.
* Decrease the default auto-complete-chars list.
* Remove company-punctuation-p, is was unused.
Update NEWS

Refs #11
company-template-c-like-templatify: use "argN" as actual field text

* company-template-add-field: Change the third argument type back; add an
  optional fourth argument; move point to the end of the field.

* company-template-c-like-templatify, company-clang-objc-templatify: Adjust for
  the above. Use `point-marker'.

* company-template-field-at: Extract from `company-template-forward-field'.
company--multi-backend-adapter: Use each respective backend's prefix
Revert "company--multi-backend-adapter: Use each respective backend's prefix"

This reverts commit a982f0fe043c31aca1a11a663c41c33b76ef0c19.

Maybe re-apply later; will have to save the correspondence between candidates
and backends, e.g. for company-strip-prefix.
Release 0.6.8