Should be able to link to other issues

I don't know how to link to other issues in issue and commit messages. I think this would be very helpful.

Good idea, will try and do something simple here.

Done! It will pick up on #ID from cset descriptions and make links out of them, and strike them through if they're not open.

So does this link to #17, then?

From comments, at least, it does not work yet. I suggest it be made to work from both issue texts and comments, too.

It does now.