Support for international characters on hashtags

To improve the utility of hashtags for international users, they should accept accented characters. Other apps that use hashtag already does that, like Twitter and Facebook.

The change made is really small, just using the list of accented characters taken from [Twitter text handling libraries][1] instead of the current character group.

[1]: https://github.com/twitter/twitter-text-java/blob/431b6ad44158c4a4a38d80d34df5b101ae2559fc/src/com/twitter/Regex.java