This is a major refactor of the links subparser, previously known as anchors subparser.
Closes#355, #534
BREAKING CHANGE: `excludeTrailingPunctuationFromURLs` option was removed. This is now the default behavior
One or more spaces before the language declaration of a code block is supported by Github.
E.g.
``` html
<div>HTML!</div>
```
``` html
<div>HTML!</div>
```
```html
<div>HTML!</div>
```
Closes#569
