2.0.1 emojis bugfix / supported

[Rodsevich]

The text with emojis was trimmed on a character. This bugfix solves that, bumps for a new version, and introduces 2 more tests for ensuring the feature behaves well

[signmotion]

Fixing the bug has taken a bit longer. If you need a Unicode-aware version of this wonderful library, here is one of the solutions: https://github.com/signmotion/fresher/blob/master/lib/src/emoji_template.dart

Also sometest for @jonahwilliams that detects this problem:

test('emojies', () {
  final t = Template('## 🙋‍♀️🙋‍♂️Thanks, {{name}}');
  final r = t.renderString({'project_title': 'Jonah'});
  expect(r, contains('Jonah'));
});