#14 - Node Soft Links Can be Made via Node Paths

[TheWover]

Node soft links can now be made via node paths, such as the following.

Examples (all valid):

---
id: node-123
title: Chapter 1
links:
  # By ID (preferred by system)
  - node-abc
  # By path (with extension)
  - nodes/Characters/Alice.md
  # By path (extension optional; .md assumed)
  - nodes/Places/Village
---

Please note, if the user manually adds a link to another node this way then it will remain one-way unless they also add a back-link to the other node. Until #20 is resolved, those links will not appear in the Mind Map.