Fix url being matched to end of message

In the url matching character class, `\u0000-\uFFFF` was matching spaces as well (this is pretty much [what `.` does](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp)), so any text after the url would be consider part of it. Changed to `\S`, to stop at blank spaces. It's unfortunate that JS does not support unicode regex patterns, it's hard to be more specific in the character class :/.

Tried to make this change as simple as possible as the regex as a whole is pretty complex. It has some features I didn't understand, like why specifically match urls within (), [], {}, <> and so on? I think this can be greatly simplified if those special cases were removed.