splitAST does not split sentences within link titles

[kimburgess]

Closely related to #24—possibly more controversial.

When provided with an input of:

{
  type: 'Paragraph',
  children: [
    {
      type: 'Link',
      title: null,
      url: 'https://example.com',
      children: [Array],
      loc: [Object],
      range: [Array],
      raw: '[This link has more than one sentence. It has two lines.](https://example.com)'
    }
  ],
  loc: { start: { line: 1, column: 0 }, end: { line: 1, column: 78 } },
  range: [ 0, 78 ],
  raw: '[This link has more than one sentence. It has two lines.](https://example.com)'
}

The following is returned:

{
  type: 'Paragraph',
  children: [
    {
      type: 'Sentence',
      raw: '[This link has more than one sentence. It has two lines.](https://example.com)',
      loc: [Object],
      range: [Array],
      children: [Array]
    }
  ],
  loc: { start: { line: 1, column: 0 }, end: { line: 1, column: 78 } },
  range: [ 0, 78 ],
  raw: '[This link has more than one sentence. It has two lines.](https://example.com)'
}

However these are equivalent representations:

[This link has more than one sentence. It has two lines.](https://example.com)

[This link has more than one sentence.
It has two lines.](https://example.com)

[azu]

Yes. Currently, splitAST parse only Str node and it parse shallow.
https://github.com/azu/sentence-splitter/blob/1663ab26ba4ad29d9ab36616a572231a5e9d637c/src/sentence-splitter.ts#L182-L191
As a result, this library does not psers Str of Link or Strong.

<Paragraph>
  <Str>  ← will be parsed  (depth: 1)
  <Link>
     <Str> ← will not be parsed (depth: 2)
   </Link>
   <Str> ← will be parsed (depth: 1)
</Paragraph>

The reason of this behavior is similar reason to textlint-rule-helper's isPlainStrNode(node).

• [Common Situation] Want to ignore a Str node that is wrapped by Link, BlockQuote etc #16

For example, the link to external blog that's Str(link title) is not under your controll.

However, it is reasonable that we can handle Link's children.

If we add recursive option, we can resolve these issue #24 #25.
Or, add handling to more types Link and Strong etc...
https://github.com/azu/sentence-splitter/blob/1663ab26ba4ad29d9ab36616a572231a5e9d637c/src/sentence-splitter.ts#L191

We need to add new behavior as option.