lispy.el: update goto machinery

* lispy.el (lispy-goto): Now takes arg. When non-nil, call
  `lispy-goto-projectile'.
  (lispy-goto-local): Deactivate mark.
  (lispy-goto-projectile): New function.
  (lispy--fetch-tags-recursive): Omit .cask.
  (lispy--fetch-tags-projectile): New function.
  (lispy--fetch-this-file-tags): Use full file name.
  (lispy--current-tag): New function.
  (lispy--select-candidate): Use helm's :preselect.
  ("goto"): re-define "f","l","b", add "p".
  ("other"): add "g".