link-rendering handler (CAN)

Backlinks

• CANs link command should enumerate links for the named note
  • The link-rendering handler should listen for the COMMAND_LINK event and render the correct list of links. Each link should be on a separate line. Each link should have the link title text and the URL.
• CAN's link command should enumerate links for the last rendered note
  • The last rendered note should be stored by the link-rendering handler (inspired by the actor model - no other code needs to be aware of this state)