!stalk name or !stalk x name to get the last (1 or x) message(s) by name

as of writing this prototype depends on overruslelogs.net so consider it simply a proof of concept

if i had some other endpoint that had chat logs for each user in line format, that would work too.

we could also cache every message locally, but that might get unweildy, maybe we need some kind of database? @sztanpet what do you think?
why not just use a regexp for this, it would make it more readable and would also get rid of the isNaN calls