Links with multiple underscores are not recognized

[sethladd]

Consider this code:

import 'package:markdown/markdown.dart' as md;

main() {
  String input = 'Hello [WORLD_TWO_UNDERSCORES] but this works [HELLO_WORLD]';

  md.Node _linkResolver(String name) {
    return new md.Text('XX $name XX');
  }

  print(md.markdownToHtml(input, linkResolver: _linkResolver));
}

Output:

<p>Hello [WORLD_TWO_UNDERSCORES] but this works XX HELLO_WORLD XX</p>

Expected:

<p>Hello XX WORLD_TWO_UNDERSCORES XX but this works XX HELLO_WORLD XX</p>

FWIW, If I remove new TagSyntax(r'_', tag: 'em'), from the top of inline_parser.dart, it works.

[sethladd]

cc @keertip for FYI

[sethladd]

Much appreciated! Thanks for the quick turnaround.