org-mac-link.el: Add support for Evernote Note Links
(org-mac-grab-Evernote-app-p, org-mac-evernote-path): New custom
variables to control Evernote grabbing
(org-mac-evernote-note-open): New function to open an Evernote note by
ID
(org-as-get-selected-evernote-notes,
org-mac-evernote-note-insert-selected): New functions to get the
selected Evernote note(s) and insert them into current buffer
Note this change also defines a new link type ("mac-evernote") via a
call to “org-add-link-type”.