Shortcut Reference Links do not work in Hybrid Editing

[Crissov]

Typora handles full reference links [title][arbitrary-id] and collapsed reference links [readable-id][] transparently, but fails with shortcut reference links [readable-id]. I'd also like to be able to convert between these easily. #985

[Crissov]

Test cases

- [foo](foo)
- [foo][foo]
- [foo][]
- [foo]
- [foo] [foo]

[foo]: /bar

<ul>
<li><a href="foo">foo</a></li>
<li><a href="/bar">foo</a></li>
<li><a href="/bar">foo</a></li>
<li><a href="/bar">foo</a></li>
<li><a href="/bar">foo</a> <a href="/bar">foo</a></li>
</ul>

- [foo]
- [   foo   ]
- [FOO]
- [*foo*]
- [_foo_]
- [[foo]]
- [![foo](bar)]

[foo]: /baz
[*foo*]: /quuz
[[foo]]: /lorem

<ul>
<li><a href="/baz">foo</a></li>
<li><a href="/baz">  foo  </a></li>
<li><a href="/baz">FOO</a></li>
<li><a href="/quuz"><em>foo</em></a></li>
<li>[<em>foo</em>]</li>
<li>[<a href="/baz">foo</a>]</li>
<li>[<img src="bar" alt="foo" />]</li>
</ul>
<p>[<a href="/baz">foo</a>]: /lorem</p>

- ![foo](foo)
- ![foo][foo]
- ![foo][]
- ![foo]
- ![foo] [foo]

[foo]: /bar

<ul>
<li><img src="foo" alt="foo" /></li>
<li><img src="/bar" alt="foo" /></li>
<li><img src="/bar" alt="foo" /></li>
<li><img src="/bar" alt="foo" /></li>
<li><img src="/bar" alt="foo" /> <a href="/bar">foo</a></li>
</ul>

[vassudanagunta]

Another example for #369.

[abnerlee]

may be covered by #985

[asherber]

I'm interested in this as well.