company-elisp-candidates: Recognize when inside varlist

* Extract -candidates-predicate and -globals.
* Add tests.
* Rename -parse-local to -locals, accept just one argument.
company-elisp-locals: Differentiate local function and variable bindings
company-elisp-locals: Skip current varlist
company-elisp-show-locals-first: New defcustom
company-elisp-candidates: Deal with duplicates
company-elisp-candidates-predicate: Blacklist specific special forms
company.el: lexical-binding: t
Fix NEWS entry
Fix #6

Same problem and solution as in capitaomorte/yasnippet#296.
Release 0.6.5
Change the summary in generated -pkg
company-elisp-var-binding-regexp: The three def macros also have cl versions
company-elisp-show-locals-first: Add keywords to the defcustom
company-pseudo-tooltip-frontend: Redraw less often when expanded upward
company-elisp-fun-binding-regexp: Consider cl-flet*
company-grab-lisp-symbol -> company-elisp--prefix; mark other privates
company-elisp: Don't complete defun name or arglist
company-manual-begin: Clear `explicit-action` when no candidates