Fixed build for irsc

Hey, I fixed the travis build for the current irsc making it work with rust nightly (24/12/2014).

Its been a nice quiet christmas afternoon here so I thought, why not play with Rust and try and build an IRC bot? Figured I'd fix your library in the process.

I haven't really improved anything, just updated the syntax where required to make it compile. I had to unwrap the results from the regex matches which now come inside Option structs and cast the function pointers when registering event handlers for the callback.