lispy.el (lispy--tag-name): Return only tag name

* lispy.el (lispy--tag-name-and-file): New function to replace old
  `lispy--tag-name'.
  (lispy--current-tag): Improve
lispy.el (lispy--select-candidate): improve :preselect
lispy.el (lispy-tag-arity): add `advice-add'
lispy.el (lispy-command-name-face): add

* lispy.el (lispy--tag-name-elisp): Elisp commands are now propertized
  with `lispy-command-name-face' during `lispy-goto'.

This face currently just inherits from `font-lock-function-name-face',
but it can be customized. This allows to get an overview of current
package's interactive abilities.
lispy.el (lispy-expr-canonical-p): fix
lispy.el (lispy--select-candidate): fix
lispy.el: update bindings

"D" is now `pop-tag-mark' (was `lispy-describe').
"xh" is now `lispy-describe' (was unbound).

Now the "follow"/"go back" combo is very ergonomic at "F"/"D".
The global bindings for "follow"/"go back" are still "M-."/"M-,".
lispy.el (lispy-occur): add and bind to "y"

* lispy.el (lispy-occur): New function.
  (lispy--occur-action): New function.
  (lispy--occur-start): New variable.
lispy.el (lispy--modify-tag): fix

Fixes case of:

    (setq foo)

Here, the `lispy-tag-arity' gives 2, but only 1 was provided.
lispy.el: update occur

* lispy.el (lispy--occur-beg): Rename from `lispy--occur-start'.
  (lispy--occur-end): New var.
  (lispy--occur-action): Update.
  (lispy--occur-buffer): New var.
  (lispy-occur): Now tracks selection.
  (lispy--occur-regex): New function.
  (lispy--occur-update-sel): New function.
  (lispy--occur-get-line): New function.

* lispy-pkg.el: add dependency.

* Cask: add dependency.
lispy.el: simplify occur
lispy.el: checkdoc
lispy.el (lispy--occur-update-sel): simplify/improve
lispy.el (lispy-tag-arity): add `cl-defun'
lispy.el (lispy--eval-elisp): improve
lispy.el (lispy--tag-name-elisp): works for `define-derived-mode'

* lispy.el (lispy--tag-name-elisp): Improve.
  (lispy--tag-sexp-elisp): New function.