Remove golog dependency

I realize the chances of you accepting/wanting this change is almost zero, but I think you deserve the right to say "no thanks, go away" at least. :)

The goirc package is awesome, and I'm sure golog is too. However I don't use golog and it's annoying to have goirc add a bunch of (to me, irrelevant) flags to the program and print warnings/errors to the console, none of which is of interest to the (my) user. That was an unwieldy sentence; the point is there's nothing really wrong with the functionality, but it's a bit invasive for what I expect from an IRC package. From a library point of view, I would expect silence if the problem is retryable or ignorable, an error return if it isn't (or perhaps an event in this case) or a panic if it's a programmer error.

(I considered writing a thin wrapper around the golog stuff and using build tags to either leave it as is or just stub out all the warnings etc, but considered it too much work for what only I needed. If you want to go down that route, I'll be happy to do the groundwork.)