* [REFACTORING]Use DocumentContext during parsing Markdown
* Add test case for hash in link
* Make DocumentContext derive Debug
* Add in_link field in DocumentContext
* Don't make hash words tags in link
* Add test for atmark in link
* Don't make atmark words in link mentions
* Add test for Persian language hashtags
See https://github.com/Plume-org/Plume/issues/757
* Add regex-syntax with unicode-perl feature to dependencies
* Install regex-syntax
* Allow hashtag to use Unicode word characters
* Run cargo fmt