Changeset a949b43 for irc_im.c

Remove old skype plugin. Use the skypeweb purple plugin instead.

RIP

This plugin relied on the skype linux client, which doesn't work
anymore. During login it just does exit(0) for mysterious reasons.
I guess that's the server trying to say that it's not supported.

This is officially dead now after a few years of kinda-almost-working.