Add clickable coordinates in chat

Coordinates that are input during chat are now clickable. They will center a user over the hex as well as select that hex and highlight it.
you should comment your regexes :)

I read this as two capture groups separated by a comma, optionally padded with spaces, that each contain 1-3 digits and optionally are prefixed with a minus sign. Looks good.

Consider using a regex builder to break it out, but it is simple enough that a comment should suffice.