allow unicode characters in hashtag

[andrewgodwin]

I'd like some tests with this that verify that it does, indeed, allow unicode characters that can be considered words (and does not allow, say, whitespace classes). The existing tests are in tests/core/test_html.py - you can add a few cases under the existing hashtag test in test_parser.

[alphatownsman]

test added. lmk if more is required.

[andrewgodwin]

That looks good - thanks!