The old regex, adapted from the other plugins, was a bit too open for
matching. This leads to matching something like: `This is a sentence:
[And something with a: in it.]()` which doesn't become a link anymore.
Because the match is: ` [And something with a`.
This patch provides a fix for the regex to only match non-space string
within the `:`'s.
References:
- Introducing commit:
2063eb8bdf
- Inspirational source of the original RegEx:
2063eb8bdf/public/js/extra.js (L1095)
Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>